I think it's safe to say if the community can think of it the developers have already considered it, although it's nice to believe they listen to suggestions which helps sway their opinion of what to include.
As the relics are class specific (with the exception of the 'no class' relic) it would be nice to see some more universal yet awkward ones (limited ammo, ammo/cash bleeds out) etc.
I strongly believe they do try to add what the community is asking for although any big feature changes such as Chaos mode were always in the planning. Whereas things like hunted being removed from MP came down to them monitoring statistics and seeing that the game mode wasn't mainstream (Nobody likes the sight of an empty lobby). I'm not sure if Drop Zone was added because of community demand or was always in the works, what I do know however is that I have quite a lot of friends who were still playing MW3 just for the Drop zone factor
I also think Extinction Hardcore was added because of Player demand.
I think Extinction has the high possibility of being a potential clan game. I would love seeing something not exactly like PvPvZ, but something competitive like score or kill for teams in either a single game, or make a big ass clan map, kinda like nightfall. Instead to make it more fair, even out all the loot on each side, amount of enemies and types, and like on mayday with the mobile drill, have it go down the middle and have it keep going through the areas on its own. Maybe wait for 2 minutes between hives before the drill keeps going and new areas unlock and the ones behind close off, keeping everyone moving forward. Make a big ass gap for the drill to go through so both sides can shoot down there, but also at aliens across too. Then in the last area or so before the boss, force the two groups to merge and work together to survive. It could work.