I smell custom playlists ala Halo 3 / Reach
I could totally see custom play list.
FIGHT THE GIANT! - 7 Players vs One Giant oversized player.
SMASH ZOMBIES! - A sort of survival match where if a zombie character attacks you with a smash or tilt you die instantly. Players can use items and they fall at high drop rates and item attacks kill zombie characters easier. Last man standing wins!
Can we think of some others? I hope the game comes with larger maps, you know... if we have 4 on 4.