What Marvel Mystery Movie Is Coming In 2018?

'Wolverine' and the 'Fantastic Four' will continue their franchises in 2017, but what secret exciting thing is coming the following year?

Marvel comics fans, prepare to put on your party pants! And also, prepare not to remove your party pants until several years from now, because the road map for superhero-related thrills now extends all the way to 2018.

The news is that Fox has announced the official release dates for a spate of new films: a Fantastic Four sequel will hit theaters July 14, 2017, and the next installment of the Wolverine franchise is coming March 3, 2017. But most exciting of all is this: an undisclosed Marvel mystery movie, slated for July 13, 2018.

Needless to say, the theories are flying this morning about what that last film might be. Below, we round up three possibilities in order of credibility.

An X-Men/Fantastic Four Crossover

This idea has been evidently in the works since Marvel icon Mark Millar came on as a creative consultant at Fox; Millar as much as confirmed that the studio's long view was to bring these superhero teams together.

That's no problem right now for the X-Men franchise, which has been going strong for years, but marking the crossover down for 2018 would mean plenty of time for the Fantastic Four reboot to get on its feet, too, especially with a sequel already on the slate.

The Big-Screen Debut of the X-Force

Equally as possible as an X-Men/FF mashup movie is this: the long-awaited release of an X-Force film, featuring Deadpool (introduced in "X-Men Origins: Wolverine") and fan-favorite Cable.

This project has been in the works for awhile, and we've known since last summer that "Kick-Ass 2" scribe Jeff Wadlow was working on a script. With so many sequels featuring familiar faces on the horizon, it wouldn't be surprising if Fox were planning to inject a little fresh blood into its existing superhero roster.

The Avengers 3, Featuring Spider-Man, Fantastic Four And X-Men

Okay, bear with us: yes, "Avengers" is with Disney, "Spider-Man" is with Sony and "Fantastic Four" and "X-Men" are with Fox.

But an Avengers threequel is definitely happening, and Summer 2018 would be about right for a potential release. Plus, with Sony's "Amazing Spider-Man" franchise reportedly concluding with a fourth film that May, Andrew Garfield could totally headline the last Spider-Man movie while still making an "Avengers" cameo.

Put the sets close together enough, and he could toddle on over there for an afternoon without even having to take off his spandex! Not to mention, Spidey himself has expressed interest in doing a spot of avenging.

Throw in "X-Men" and "Fantastic Four," and you have potentially the biggest movie of all time. The barrier, of course, is that the rights are all over the place, and the various studios have no interest in working with each other. But with entertainment companies looking for new ways to capture the rapidly fragmenting audience, is a superhero singularity that far off a possibility?

Fox, Sony and Disney: Let's make this happen.