It's the movie that comic book fans, and especially Marvel devotees, dream about: an epic that brings together the Avengers and the X-Men in one mighty big-screen blowout.
Way back before Marvel became its own self-sufficient studio (now operating under the Disney corporate umbrella), the company farmed out the rights to its characters to various other studios. That's how Spider-Man and Ghost Rider ended up at Sony Pictures, the Hulk landed at Universal and the X-Men and Fantastic Four found a home at Fox.
But as a result, most of those characters can never appear in a homegrown Marvel movie—not unless one of two things happens: either the studio that owns the rights to a particular character lets them revert back to Marvel, or the two studios agree to some sort of special permission or even a co-production deal.
The rights thing already happened with the Hulk and more recently with Daredevil, but as for the second option, well, the studios are just too competitive to want to share in the profits and glory of some kind of crossover movie—even knowing that it would probably do blockbuster business at the box office.
One person, however, who's all for such an arrangement is Lauren Shuler Donner, who has produced every one of the X-Men movies from 2000's original X-Men to last year's shockingly good X-Men: First Class. Asked about putting the mutant team in an Avengers movie, Shuler told Crave Online:
I would love it. I would love it. I personally have close ties to Marvel because of (Marvel president) Kevin Feige, because Kevin worked for me. But to take our characters and mingle them in the way that they were written, yeah, absolutely.
Well, if the powerful producer of one of the longest-running Marvel franchises (six films, including the upcoming X-Men: Days of Future Past) wants it to happen, is it really that far-fetched? Couldn't the studios be made to realize that Avengers vs. X-Men (or whatever it ended up being) would be a license to print free money?
After all, we already almost had this small step—and you know what they say about small steps ...