Ten years ago I would have told you there would never be an Avengers movie that grew out of a slew of superhero solo films. Couldn't happen, I would have said. Hollywood doesn't work that way.
Except now it does, and Marvel Studios changed the entire landscape of the blockbuster business. Could they keep changing it? Never say never again, I guess. While it seems unrealistic to hope for a crossover between Fox's Marvel properties (Fantastic Four and X-Men) with the main Marvel properties, it isn't totally impossible.
One of the people who would be on board is Lauren Shuler Donner, the producer who has shepherded the X-Men films from the beginning. Talking to Crave Online she says:
I would love [to cross them over]. I personally have close ties to Marvel because of Kevin Feige, because Kevin worked for me. But to take our characters and mingle them in the way that they were written, yeah, absolutely.
A year ago this would have been straight up impossible, but there have been big changes at Fox, with Tom Rothman leaving the big chair at the head of the studio. Might the new regime look at the idea of a crossover and see that it's win/win? Having Captain America show up in The Wolverine only serves to energize the fanbase, and would make the movie more of an event. The crossover possibilities are endless and organic, and wouldn't have to be something as elaborate as the recently concluded Avengers vs X-Men miniseries - just having The Beast show up in The Avengers 2 would be a nod to the history of the character (who has been a member in good standing of the Avengers for a long time). Hell, allowing Magneto to be mentioned would make Quicksilver and Scarlet Witch more likely to appear.
So yeah, this is non-news, but I learned long ago never to dismiss any possibility when it comes to Marvel Studios.