So 20th Century Fox owns Wolverine

An X-men/Fantastic Four movie has gone nowhere because they haven't been able to make a successful Fantastic Four that will elevate their X-men universe as opposed to bring it down. However, much of what Fox has been doing since "The Avengers" debuted to big numbers has been to work toward that aim. Originally they wanted to create a shared universe with those two properties plus Daredevil, but they didn't have enough time to pull a movie together before the clock ran out on the Daredevil rights and they didn't want trade Galactus for an extension because they considered the Fantastic Four property to be more valuable.

At that point, they continued to move forward with their Fantastic Four reboot despite also being dangerously close to the deadline because the idea of a shared movie universe had them seeing dollar signs. However, things weren't looking good for them. They had to delay plans for the movie a couple of times until they reached the point where they were working up against a wall. Meaning, they had to rush the movie into production or they would lose the rights. It seemed to me from the beginning that Fox realized they didn't have the time to do a proper reboot so they ended up cutting down its budget. Although I'm sure they were hoping to be able to recoup their expenses, it seemed as though they had given up on the idea of putting out a good movie and instead just wanted to put something out to preserve the movie rights for another ~7 years.

Now that the clock has been reset, I wouldn't at all be surprised if they're back to working on plans for another reboot that they can join together with their X-men universe. They have plenty of room to breathe now so they can take their time on it and probably don't want to rush out an announcement as emotions are still a bit high after their last reboot attempt failed.

Anyway, all of that is to say that they've publicly put too much effort into trying to craft a shared movie universe for them to need Marvel's permission to move forward with it. Their problem is simply that they never imagined doing any such things and had given up on Daredevil and the Fantastic Four are viable properties until "The Avengers" came out and led them into a fourth hour scramble to try to put something together. That they had so little time together to do something or lose those properties is why it hasn't happened.