I don't know why this has never been discussed (or maybe it has and I've just repeatedly missed it!) As a huge Marvel fan I am truly disappointed that all my favorite characters film rights have been split up between Fox, Sony and Marvel Studios. This means that even though all our Marvel characters come from a shared universe in comics and cartoon they can't co-exist in their cinematic versions.
We know that Spiderman is over at Sony, and since they own the rights to him, his stories and related characters we can't hope for much crossover with him and the Avengers, X-Men or Fantastic Four.
Iron Man, Thor, Captain America, mainly the Avengers, all still remain with Marvel Studios.
Finally, over at Fox Studios we have the rights to the X-Men related universe, and the Fantastic Four.
So this means we won't see Spiderman team up with Iron Man, or Hulk and Wolverine fight....but with Fox owning both the rights to X-Men and the Fantastic Four we at least see a chance of something happening! These teams have had many crossovers in the decades of comic continuity. Storm even had a short time where her and husband Black Panther led the Fantastic Four in Sue and Reed's absence!
Unfortunately Black Panther's rights are over at Marvel Studios with the rest of the Avengers so that's unlikely....but still! I'd love to see Iceman and the Human Torch team up! Or just see an all out brawl between Cyclops, Mr. Fantastic, Storm, Rogue, Thing, and Invisible Woman!
My biggest thought is: WHY NOT? We know the Fantastic Four is being rebooted with an expected movie in 2015, why not make it line up with the X-Men cinematic universe and have a crossover movie maybe sometime around 2017? If done right Fox could easily hold onto these movie rights for decades longer.
So I say: WHY NOT?
What do you say?