There are a few good ideas they could do but for now it does really seem like “yep, that’s it”.
One idea i had was adding a last stand mode.
That way you have a potentially endless game mode where things keep ramping up and ramping up until you literally cannot deal with hordes or anything they throw at you anymore.
Adding more battle conditions would be cool but i think the current mission board either needs to go entirely or needs an overhaul where the missions popping up are special contracts and you can pick whatever you want.
Edit: I think the above point has been proven somewhat be the inclusion of shock trooper gauntlet. A lot of people are mad that Hi Damnation seems to be gone and they can’t get the modifiers they want and as a result are kind of stuck with what the board give them. In theory being able to mix and match would be nice however in practice the current mission board just does not work with this system.
Another option would be adding a DRG style weekly mission called a Hive Expedition where it’s 3 missions back to back with extra hard modifiers and you keep your current hp / ammo / grenades / status between missions and each mission has a set modifier / extra objectives before you can leave (maybe on top of doing the main objective you need to kill x number of mutants or find a certain amount of pastel) and completing the 3 mission run nets you a large pile of resources, a high level emperors gift, and maybe something else.
Going along that same idea Payday 2 has a crime spree which is another string mission style system that keeps stacking modifiers and enemy changes in a similar style to Chaos Wastes until you cash in.
There is a lot that they could do but overall it’s just not a whole lot in currently.