I am no dev, so also awaiting an accurate answer... However, in the past while I modded Insurgency (2014) we were able to configure most server variables and settings through the server files (ie. Server.cfg, Gamemode.cfg, Gamemode.theater) and that enabled insane Coop servers and the PVP Competitive scenes that spread around the world. With my experience also modding the UE4 game ARK: Survival Evolved, I expect that we will again have a wide range of features to tweak. This might not be available in Alpha or Beta, etc. but I do expect it upon full release or release of open dedicated hosting. Hope this helps, but it's probably what you already presumed as well.
Keen for a dev response!
I think we'll get mutators from UE4 engine that coded in C++.
It works like server mod and if you're interested you can search more about this and try to host a server that with mutator support in UE, such as Killing Floor 2 and Rocket League (only in Private Match).