I hated Marvel vs. Capcom 3, so I'm not interested in this game. Especially it might not have any characters from X-Men and Fantastic Four and they went back to the 2 on 2 tag system.
The only good thing about this game is they actually added Mega Man X to the roster and he's not going to be a alternate costume for Zero this time around. That was a dick move by Capcom on what did in MVC3 along with making Jon Talbain a alternate attire for Amaterasu instead of making him a standalone playable character.
Hopefully they'll bring back Venom this time around, but I doubt it.
I still think Marvel vs. Capcom 2 is the best game of the versus series in my opinion.