I'd like another WWII shooter, I know they're all over the place but we haven't had a good one in a while! (If there is a good one that I've missed please tell me)
Hell maybe even a WWI shooter would be a great change (I know the circumstances of the war, not exactly FPS gold but the game Verdun pulled it off perfectly)
The chances of either of those happening are relatively slim, as the games follow trends to please the majority and its all about the future now I guess.