Universe crossovers apparently are the thing in the superhero movies right now. Marvel started the trend and due to the immense success they're reaping, the other movie studios are likely to join the bandwagon. Right now, there are talks that 20th Century Fox is already planning a big one. 

What cards does 20th Century Fox have? "X-Men" and "The Fantastic Four." There are already rumors about the two comic book teams of superheroes joining forces in one movie. Producer Simon Kinberg never denied their interest in crossover universes, but of course, he doesn't want to spoil anything just yet. 20thCentury Fox has not dropped a clue about it either. 

However, the recent email hacked from Sony Pictures tells a different tale. According to The Daily Beast, there is solid evidence that a movie featuring the X-Men and the Fantastic Four is already in the works. 

In an email to Sony Pictures Entertainment co-chairman Amy Pascal, Columbia Pictures production co-president Michael De Luca specifically said that he had heard from Kinberg that Fox is already working on the "X-Men" and "Fantastic Four" movie crossover. Additionally, De Luca suggested to Pascal that they may want to do the same with the "Spider-Man" movies, linking Spider-Man, a female Spider-Man, Venom and the Sinister Six characters together. 

Cinema Blend got a hold of the synopsis of the "Fantastic Four" reboot and it said that the team will get their powers by teleporting to an alternate dimension. If this will be the story arc they're going for, it's not really hard to make them meet with the X-Men in another world. 

Nevertheless, these are still unconfirmed speculations, which everybody is really hoping to happen. The email hack is good evidence though. The reason why Fox hasn't revealed anything yet is that, maybe, they haven't gotten the official greenlight yet, reports Cinema Blend. And also, they might want to wait until the "Fantastic Four" trailer comes out and see how bankable the movie is before moving forward for a crossover.