Even through the bitterness behind how MvC3/UMvC was handled, I still maintain, MvC4 is too strong of a brand and seller. Present Marvel licensing team knows, the old team was super enthusiastic about it, and it has a great recent sales record. It's about a no-brainer as it gets, especially with the proliferation of the MCU.
A modern licensing contract wouldn't have any of the stuff that made UMvC3 what it was, because those games in that contract were in the oven so long, and from a time when digital distribution was still in it's relative infancy. Capcom having the budget, being willing to take that financial risk, and dedicating enough resources/development time to it are equal parts the problem, but not insurmountable and wouldn't be surprised if the wheels are already in motion. I think we'll see an announcement by 2018, if it's not already one of Marvel's remaining games to announce this year.