It was in the old rules. In the new ones, the worst result is that yous psyker explodes in a war power explosion blast that wrecks everything around him. In the old ones, he could get posessed, which gave him a bonus of +2 to all his stats (a big buff) and inmune to psycology, meaning that a posessed psyker could engage 3 gangers and you could expect the psyker to win and want more. Also, since it's posessed he would engage any nearby unit, be it yours or the enemy. Dunno if they will implement this or not, because it also means that your psyker is dead because he is posessed by a chaos daemon, and your gang puts him out of his misery if he still lives at the end of the fight.
In all due honesty, i hope we have permanent gangs in the game because that would mean you would fight harder or easier fights from time to time. Some gangs with high reputation would have these special units while others would have simply more gangers instead of mirror matches like in Mordheim (enemy warbands always had the same rating as your, meaning that you always fought a mirror of your warband in terms of strength). Still, there is always a way of bring down of these huge guys. But you have to remember to pray to RNGsus for it to work properly.
I know we want our favourites, but in this case i have 2 reasons to think that a chaos space marine in the underhive of necromunda is an almost impossible scenario: chaos space marines attract a lot of attention from everyone because of their huge rampages typical of blood crazy maniacs and the fact that there is a space marine base in Necromunda (Imperial fists if i'm not mistaken). That summed up with the stern control that Lord Helmwar keeps in the hive makes it incredibly unlikely that some Chaos Space marines are wandering the underhive. And so for Chaos Daemons, since they need a steady supply of chaos energy to stay in the material world (something that was possible in Mordheim due to the inmense amount of warpstone in the city). But still, finding some Chaos cultists in the underhive is a very high possibility, and the same goes for Genestealer cultists.
For the reasons of other races to be in the underhive, the Dark Eldar is the simplest: they need slaves. They will be glad to take slaves since Dark Eldar are known for stealing entire planets. And knowing that there is an Eldar Embassy and that the noble houses of Necromunda are entagled in illegal drug dealing, it's not impossible that they have some Dark Eldar pirates in their payroll (even tho it's more likely the opposite). For the orks, they always want to fight. If you tell them there are some really tough ass people in that shiny place in the distance, they will go there in droves in order to bash their heads in and take their stuff. And then, look for even tougher people to shank and take even more stuff. It wouldn't surprise me that some Orks from the Skull venture into Hive Primus to fight gangers from time to time just for fun.
When it comes to Chaos, they will usually want to bring down the entire planet, make everyone go insane and kill as many people as possible. All for the promise of power beyond this world and inmortality. And when it comes to craftworld Eldar, i doubt they would even consider meddling with humans, mainly because they think of themselves to be far avobe us filthy and lowly monkeys. The only times craftworld Eldar do something is to prevent the rising of a tomb world, to prevent future harm to their interests (such as colonization of maiden worlds and active campaigns against them) or in fighting the forces of chaos (their main enemy).
I'm glad i got you interested on those, but first we should know how they will adress them in game. I want to know if psychic powers will be treated like magic was in Mordheim (first you roll for spell success and then if there is an after effect) and what the consequences of using the powers of the warp will be, because the worst that could happen in the Tabletop is that your psyker ends up posessed by a chaos daemon or exploding in a massive warp energy backlash.
Those special units are truly very dangeous, but they all have their weaknesses or else they would be way too strong. For example, the Stig Shambler despite being very tough, having more mobility than anyone (movement speed of 7, compared to the average of 6 and the Goliaths with 5) and having 2 weapons (the melee one with 3 attacks), it has poor ballistic skill and weapon skill. Pretty much, you will be lucky if you land an attack. But if you land it, it will hurt. Another example is the Khimerix, which despite having very high initiative, decent toughness, strength and also has regeneration, it's weak to fire (cancels regeneration) and also has poor leadership, meaning that it will run away like a scared puppy if you have 3 gangers surrounding it.
Well, those rules are from older Necromunda, but when it comes to it lorewise, they are possible (except chaos space marines and chaos daemons, or else the inquisition would be too interested in going down there). The scavvies are something many people want back in Necromunda, because in old necromunda they were quite damn strong if you played them right. If you won't know what a scavvie is, it's a heavily and grisly mutated person that has been sent to live in the far and dark corners of the underhive. Even tho in the Underhive mutation is tolerated within acceptable bounds, mutants are usually more despised than in the hive proper, and therefore most settlements openly reject them or outright kill mutants. There are other denizens of the Underhive that are worth mentioning: the Ratskins. These are considered the "original" inhabitants of the underhive and they know it like the back of their hand.
When it comes to possibilities, i really want Ork corsairs venturing in the underhive to sack and kill. Or Dark Eldar raiders taking down gangs to engross the amount of slaves they take. Possibilities are abound and we all have our favourites. But for now, let's wait until we get a little morsel from the devs. I bet they have something juicy for us, but good things always deserve the wait.
Oh yes... I have that gang war supplement and i made my own Cawdor gang. This one included a lot of new stuff and i liked the direction the game was taking with mercenaries, psykers and new gang units.
Psykers are definetly a possibility in Necromunda. In the lore they establish that there are 2 types of psykers: sanctioned (AKA trained) and unsanctioned. The main difference between both is that santioned psykers can reroll failed willpower tests, meaning that if you fail to use a warp power, you can try again and succeed. As well, in the game it stablishes that if you take down an unsactioned psyker, your gang recieves 5 credits for it (since unsanctioned psykers are pretty much outlaws). I still want to see how psychic powers are dealt with, but you can definetly get psykers into your gang, no matter which house you are.
Those other things are special gang units. Like you side, they are the equivalent of impressives in Mordheim: extremely tough and lethal, but also costly and you cannot have more than a certain amount depeding on your gang's reputation. Aside from the amazing statlines of these guys, they have a lot of special weapons and rules that makes them amazing. For example, the Escher Khimerix has scaled skin +4 (meaning it has a 4+ armor save) and regeneration, as well as poison attacks and poison breath attacks. The Van Saar arachnid rig suit has a climbing special rule that allows it to climb on any surface as well as 4 melee attacks per turn (unless you decide to turn 2 of those into ranged attacks by adding ranged weapons) and twin linked las carbines. Also, you forgot the Orlock mining servitor, which is a heavy weapons platform that can shoot and move in the same turn and has a +1 bonus to ammo rolls, meaning that this guy is truly damn dangerous.
My all time fav is the Stig Shamber, because it is a heavy weapons platform that also is very dangerous in melee. And thanks to his special rule, it can re roll failed leadership tests. Overall, all these units mean a lot of business and i want to see how they are implemented. Mainly because of their special rules (being regeneration the most tricky).
I also want more armors than Light, medium and heavy. In old necromunda there were several types of armor or combat suits (Mesh armor, carapace armor, flak armor, camaleonine...) but in current edition necromunda Flak armor is kinda the "normal" armor even if in old edition it would be heavy armor, but in the new edition you also have the reinforced underplate, which grants a bit of extra armor. I hope we get a lot of variety when it comes to armor instead of just 3 types, making you able to customize even more your gang. And when it comes to sync kills, that's up to the devs, but it would be a nice touch.
When it comes to capturing gangers i wonder if it will be implemented and how will it be. I can definetly see the "you take the stuff this guy had" thing and also the chance that he has a subdermal blade and he escapes, but this is a question for another time.
As for permanent injuries, of course you can replace missing limbs. In Necromunda you have bionics in order to "salvage" a ganger with a missing arm or leg, since basic bionics are not as good as an arm or a leg. Eventually you can buy advanced bionics which are better, but that's a matter of money. Also i want them to expand on the permanent injury system, implementing things like old wound (random chance a ganger cannot fight), fearsome scars (ganger inflics fear) or valiant scars (+1 leadership).
Also, if you have any questions just ask away. We may be a bunch of nerds (at least i am) but we don't eat people. Well, most of the time.
When it comes to power armor, i think you will definetly not be able to have access to it unless your gang packs enough heat to take down a spyrer or an Adeptus Arbites, and that is if they are a thing in the game. But what i hope is that we get many different variants of armor with a lot of different effects, like the nanoscale armor (armor that has less effect with every hit taken) or Camaleonine (doesn't grant armor but makes you harder to be hit with ranged attacks) rather than just having no armor, light and heavy armor.
And that doesn't mean your gang cannot have access to some truly monster weapons like in Old Necromunda like Heavy Bolters and Plasma cannons. Sure, only the most powerful and rich gangs could affort to have one, but it was still one.
Also, capturing gangers was and is still a thing in tabletop and you could either demand ransom for the ganger, sell them into slavery or put them to work in your turf (like in a mine or a toxic waste dump).
If the saboteur ends up being an explosives expert that will be interesting for 2 reasons. It will mean that maybe explosives (grenades, shaped charges...) will count as weapons and not consumable items like the Oil bombs in Mordheim. And also it might mean we will see mission objectives, such as "destroy a water depo" or "Blast a hole into a settlement wall".
Also, when it comes to classes will the deadeye be capable of using short range weapons like pistols and shotguns? Or they will be limited to long range only like LasGuns, Rad weapons and Needle rifles? And what heavy weapons will we have available? Old Necromunda had plenty of heavy weapons to choose (Las cannon, Heavy Bolter, Plasma Cannon...) but so far in the rulebook i've seen Heavy Stubbers and Twin linked Las Carbines.
Well, i'm curious if the statlines will keep being like in Mordheim, which isn't bad since we are used to them, or they will have any change. In tabletop, for example, there are 2 stats to account for: cool and leadership. While leadership is for terror, fear and all alone tests, cool is in order to perform actions in the battlefield successfully (such as using poison on a weapon, healing a comrade etc...). I wonder if they will be kept separately or they will both be compounded in Leadership.
I also kinda want to see how Leaders and Champions go in the game, because in Tabletop Necromunda champions and leaders had access to special weapons only they could wield (such as combi weapons or the more brutal ones like plasma pistols and power hammers). Now that you say it, are these classes only for run of the mill gangers or they apply as well to Champions and Leaders?
Also, when it comes to juves they can also be adressed in the same way youngbloods were in Mordheim, but i think that would be a bit too simple. I think it would be more interesting in one of two ways: either starting very weak and having higher stat growth or more skill point gain than gangers or the way i previously stated (they start very weak but once they get 1 level they become a level 0 ganger with better stats than a hired level 0 ganger).
On the topic of traps, i also want to see how they will work and how "strong" they will be in terms of damage and functionality. Traps in Mordheim were quite nice (white powder trap the best imo), but i hope we are given different kinds of traps depending on the house we play to mix it up a little bit. For example, in the lore Cawdor gangers sometimes carry trained rats riddled with bombs that they let out in the battlefield. I can kinda see the homing bomb mechanic working with the same mechanic it has in tabletop, but i wonder if we will only be limited to explosive traps or anything else.
I also wonder how they will do in open combat.
And on the other questions, here are the answers:
Space marines have access to power armor because it's given to them. The chapter provides for weapons and armor for their battle brothers. And the chapter is given weapons and armor by the Imperium at large, who manufactures it in many worlds all over the galaxy.
Gangers have no access to power armor. The closest you can get is the combat armor from the Arbites and the special suits of the Spyrers. Gangers usually carry makeshift armor and the closest you can get to armor is Mesh armor.
Chaos Daemons could appear if we get chaos cults around, but i doubt it. But you musn't rule out the feisty beasts that are in the underhive, such as giant rats, spiders and other nasty mutant creatures.
First of all, the initiative ladder is something i had kind of a gripe with, but looking back i think it was a quite decent system. Not perfect, but still good enough. The thing i'm wondering is: Will initiative be determined by agility? or by other stat (like awareness)? Mainly because in current Necromunda Initiative is like agility, being required for climb or jump tests as well as for evading special attacks, like grapples and such.
Second, i really want that they pute Juves into the game, but with a small difference. Be it as they can be recruited for cheaper than a Ganger, but they are comparatively worse than a ganger (low weapon skill/ballistic skill, poor leadership, etc), but if they get rank 1, they become a ganger instantly with their stats are slightly better than a fresh ganger. That would be a nice way of implementing Juves making you want to get a few measuring the cons and pros.
The classes look quite nice, and i want to know if aside from weapon restriction, they will all share the same skills or have unique skills per class (and also per house). I'm very interested in the Saboteur and the trap mechanic. I already can see the Cawdor Gangers releasing hordes of bomb rats onto the battlefield, but i wonder if all houses will have different types of traps or not (like Escher having poison traps, orlock having blasting traps, etc...). Still, rooting for a bit of gameplay to see a bit of the action, but i can picture more or less how they go.
I think we will definetly have spyrers. What's the point of not having them? They were extremely unique compared to all the other gangs, and the same could be applied to the Enforcers.
Still, seeing the new characters added and the new mechanics implemented (such as the rat bombs, sanctioned/unsanctioned psykers, impressives...) it's truly amazing how much work they are putting into bringing back necromunda.
But like you said, let's have first the game as a solid base and start working from there. New gangs as DLC wouldn't be all that bad as long as they bring new stuff into the table.