Well, since Disney has announced they won't make games anymore, the license for Marvel games could be bought by someone who could make a new Marvel fighting game. Capcom would be the "obvious" choice, seeing they used to own the license to make Marvel fighters, but since Capcom's current economical situation is rather bad, I don't think that will happen. And since NRS is WB property, I doubt they will be able to pick it up either.
Maybe Iron Galaxy, under Microsoft? That would mean an Xbox/PC exclusive game though. They ported the old Marvel/Capcom games though, and did a fine job doing so, so it could be a possibility. If they have the time and money to make one, that is. KI is on a budget, so a Marvel fighter would be too.
I'd love to get a X-Men fighting game, not a Marvel one. But i'd love it to look realistic (as MK and Takken), not that japanese cartoon bullshit. Roster could be somehting like this (haven't included Professor...)