Now that the Sony/Marvel collaboration on Spider-Man is happening, it's time to see who might be next.

Back before Marvel Studios was even a twinkle in anyone's eye -- let alone the superhero movie juggernaut it is now -- Marvel Comics sold the rights to many of its characters to various other studios. Aside from Sony and Universal (which still retains the rights to the Sub-Mariner, although I wish they'd give them back so that we could one day see Namor in the MCU), the biggest non-Marvel rights holder is Fox, which owns two of Marvel's most famous and iconic properties: X-Men and the Fantastic Four.

You can pretty much forget about Fox ever giving up or even sharing X-Men. Four of the five X-Men movies have made more money than their predecessors, with X-Men: Days of Future Past the biggest of them all. The Wolverine spinoffs have also done quite nicely, even the lousy X-Men Origins: Wolverine. The world of the X-Men is so wide and deep -- it's kind of its own galaxy within the Marvel Universe -- that Fox can keep making movies forever based on that alone. Thankfully, at least the quality has gone way, way up from the nadir of X-Men: The Last Stand (which wasn't even that bad) and that first Wolverine film (which was).

But what about the Fantastic Four? Fox is about to take its third swing at this franchise after the first two dreadful attempts in 2005 and 2007, with a total reboot involving a new cast, a new director and a decidedly different tone and origin story than we've seen before. We've all heard about the many rumored problems the film has faced, and the buzz about the movie in the fan community has not been strong.

So, what if Fantastic Four comes out and -- whether the film is any good or not -- becomes a flop at the box office? A sequel is already on the boards for 2017. If the first one tanks, does Fox recalibrate and give Kevin Feige over at Marvel a call, the way that Sony did to save Spider-Man?

Fox is a notoriously hardball company that doesn't necessarily play well with the other studios. Fair enough; making expensive movies and selling them to the public is not a game for pushovers. But the execs over there aren't stupid, either: they have to be watching the incredible buzz and good publicity generated by the Sony/Marvel deal, which is almost certain to turn into major profits for both companies in the next two years as they roll out Spidey's MCU debut and his next solo picture. (They also simply gave Daredevil back to Marvel after their last attempt at a new movie didn't get out of development hell, so they're not completely tight-fisted in that regard.)

If Fantastic Four comes out and lands on its ass, Fox might just consider picking up the phone after all and making the same kind of deal that has paved the way for Spidey to enter the official MCU: an appearance by the Four in an MCU film, followed by the next FF standalone entry. Just as with the webslinger, the good will and massive publicity that would conceivably come out of this could be enough to rescue Marvel's First Family from a fate worse than any Doctor Doom could dream up: box-office failure.

And if Fantastic Four comes out this August and is a spectacular, no-doubt-about-it hit? Well, the MCU will be just fine, and we'll all go back to wishing for what could have been.

But if not ... well, if you were running Fox, would you make that call to Marvel?