Marvel vs Capcom has done very well to continue on for as long a it has. While it certainly plays second fiddle to Street Fighter V in Capcom's fighting game library, any news of a release is always consumed quickly by fans.
And if this report by Polygon is to be believed, it seems we might have some very concrete information very soon about the next in the series. The report claims that not only is Marvel vs Capcom 4 real, but it will be revealed at this week's PlayStation Experience for a 2017 release date..
On top of that, this looks to be a Marvel Studios inspired joint, as it seems only characters who are owned by that entity are being included. The report says to expect heroes like Ant-Man and Groot over any of the X-Men for example. No Wolverine in a MvC game? Perposterous!
I'd been hearing murmurs about this all week, so I am inclined to believe this. Also, Street Fighter V was spoiled somewhat similiarily before its announcement at PSX too. I'd say this is probable.