I'd like to suggest an Ambush mission added to Operations.
The bulk of the missions currently are Retrieval missions (understandable since the victory condition for Operations is the total amount of resources you've acquired) interspersed with the occasional Base assault/defense, Spectrum Supremacy and Royal Rumble missions. These tend to get old and for the high-level gang there are few surprises in PvE.
The AI, while dramatically improved over the release version, still has problems dealing with a competent human player. In order to give it up a leg up, I suggest getting the AI to team up against the human player under a very specific set of circumstances.
If the human player is ahead in terms of resources, there will be a small chance (say, 10%) that an ambush will occur every time the player attempts a mission at the halfway mark of an Operation. (This would take the place of the selected mission in the same way Base defense missions do.) The chances of an Ambush mission occurring will increase the greater the player is ahead. If the human player has twice the amount of resources of the nearest AI rival, the chances of an ambush increases dramatically to, say, 50%. If the human player has thrice the amount of resources (something that can happen towards the end of Operations even on Deadly difficulty), the ambush chance goes up to 90%. Regardless of outcome, an ambush may only occur once per Operations since it would be exasperating to face ambush after ambush.
The narrative set-up would be thus: two of your nearest rivals team up against you, setting aside their differences temporarily in order to take out a more dangerous rival. (The nail that sticks out gets hammered.)
In gameplay terms, this means the player will face off against two AI gangs with the crucial difference being both AI gangs are placed on the same team. (This will prevent them from bloodying each other up before getting to your gang.)
You can currently reproduce this scenario in Skirmish mode. Set up a Contest, select two AI gangs each with 6000 rating and put them both on Team B. What happens is both AI gangs will cooperate. This results in a dramatically greater challenge even for an experienced player with a fully kitted-out 5000-plus rating gang.
To further increase the challenge for an Ambush mission, place the player's deployment zone on one end of the map with the extraction zone on the other end where the AI's deployment will be. The general concept being,"If you want out, you have to get past us first." Make sure no resources are on the map to prevent the AI getting distracted. For the player, the reward is simply survival.
This does a couple of things. It puts you on notice, preventing you from being lackadaisical once you get ahead in Operations. Furthermore, by giving the AI an advantage during Ambush missions, it makes it likely your gangers will go out of action. Now that might sound like an odd thing to wish for but the ultimate goal here is to give you a very strong incentive to have a full gang of 15 and ensure your reserve crew members maintain parity with your best gangers. As things stand currently, you can get by with only 5 gangers even on Deadly difficulty.
Granted, this would make the game is a little frustrating for new players so I suggest including Ambush missions only for Brutal or Deadly difficulty Operations. (Mordheim: COTD had something similar.)