It will become the "Hope Springs Eternal: The rights are home" thread, where we will gush about everything they can do now.
Well they can kind of do stuff with Hulk and Namor, they just can't put them in their own life action film but they can make them Avengers.
The Fantastic Four need to revert. I don't see how Fox can win. Fox should give up their cut of X-Men merch so they can afford to cut their marketing budget in exchange for the FF since I can't see a sequel working unless it goes low-budget which means getting rid of Thing for most scenes. Plus Fox did kill off a character who was a combination of both Doom and Annihilus and when you get rid of the FF's two greatest enemies, it feels too much like scraping the bottom of the barrel to use anyone else and Galactus would require a massive budget + it would just be repeating the path that the Tim Story films took. Rebooting at the same studio so soon after a flop also feels like a mistake. The only thing that can save them now is a hard reboot in the MCU regardless of which studio releases it and I don't even want a new FF film until 2020.
With the X-Men, the only way that I feel like both fans and Marvel can win is if Fox retain production rights and both studios have some level of creative control with Feige having equal input with Singer, Kinberg and Donner as to how the films are made, script and costume approval, etc. They'd need some sort of event film to merge universes. Like if the X-Men reverted in full, Marvel would need to handle the X-Men, X-Factor, X-Force and New Mutants and produce solo films for Wolverine, Deadpool, Gambit, X-23 and Cable and that's way too much for Marvel Studios' production schedule. Even with three films a year, that's way too much if Marvel ever want to give Black Widow, War Machine, Hawkeye, Falcon or Winter Soldier a solo film. Now with it confirmed that Marvel's TV side are working on Moon Knight, Blade, Ghost Rider and Cloak and Dagger, the only characters that Marvel own who can support their own title who haven't appeared in the MCU yet - or aren't slated to appear like Inhumans or Shang Chi - are the Eternals. Marvel are stacked and Fox are ramping up their production schedule. If the X-Men completely reverted to Marvel, then we'd have to see some of these options taken off the table with fewer solo films than Phases 1-3.
I mean, both studios feel limited. The Guardians of the Galaxy could really use the Shi'Ar and Badoon who are at Fox. Captain Marvel could use the Brood. Black Panther would benefit from Storm. Agents of SHIELD would benefit from Abigail Brand and GW Bridge. Rogue, Beast, Gambit, Prodigy, Wolverine, Havok, Cable, Deadpool and Storm have all joined the Avengers. And on Fox's side, Namor, Spider-Man and Captain Marvel have joined the X-Men in the comics and Wolverine has a long history with Captain America, Black Widow and Elektra while Jean Grey has connections to Misty Knight and Jessica Jones. Both universes would benefit from a merge. I just don't feel like a merge can or should happen while Fox hold on to the Fantastic Four and Universal act like petty children and refuse to let Marvel make a Hulk or Namor film.