Fox holds exclusive film rights to the X-Men (including Deadpool, Wolverine and Cable), as well as the Fantastic Four and Silver Surfer.
UPDATE on December 14: Disney announced it will purchase assets of 21st Century Fox for $52.4 billion in stock. The news means the X-Men, Deadpool, James Cameron's "Avatar" films, the "Alien" franchise and more will head to the Mouse House. Original story below.
The Walt Disney Co. will purchase assets of 21st Century Fox, including its movie and TV divisions, for $52.4 billion in stock, Disney announced on Thursday morning.
Reports are coming in that Disney and Fox are closer than ever on a $60 billion merger deal that would bring all of Fox's movie assets into the House of Mouse and fans of Marvel Comics are paying very close attention. A deal would unite Marvel's "Avengers", and Fox's "X-Men" and "Fantastic Four" under one roof, opening the door for a slew of classic Marvel Comics stories to make their way to the big screen.
The timing of this possible merger coming as soon as next week makes sense, as Marvel Studios has been playing coy about their plans beyond the fourth "Avengers" film in mid-2019, or what is known as "Phase 4." They have hinted at stories across time, realities, and even a possible reboot.
They might have been awaiting the conclusion of this deal in hopes of either incorporating these classic characters into the Marvel Cinematic Universe, or instituting a line-wide reboot of the franchise with the Fantastic Four and X-Men front-and-center from the very beginning. That alone would make it different enough that MCU fans wouldn't even be able to complain that they'll just rehash old stories.
If they decide to forge ahead with current continuity, the Fantastic Four and their ancillary characters would be key additions to the announced plan to go more cosmic in the next phase. The FF bring with them classic alien races like the shape-shifting Skrulls, and cosmic menaces like Galactus, the world devourer, and his herald Silver Surfer.
A reboot could offer a fun nod to Marvel Comics fans, they could call it the "Ultimate" MCU in a nod to a spin-off imprint created in 2000 to re-introduce Marvel's characters to a new generation. A reboot could also launch with "Fantastic Four," which also launched the Marvel Age of Comics in the 1960s.
Either way they go with it, a merger of these two entertainment juggernauts means fans will finally get the chance to see epic crossover events from the comics like "Avengers vs. X-Men," "Secret Invasion," and the original "Galactus Trilogy." Here are the stories TooFab is hoping for:
The Galactus Trilogy 
The original saga didn't really feature anyone outside of the Fantastic Four, but it introduced Galactus and the Silver Surver to the Marvel Universe, and even when it came out, fans were wondering why no one showed up to help. Galactus, after all, is a cosmic being who literally devours planets and destroys everything on them. This is crisis-level stuff and should be all hands on deck. The story also serves as a redemption arc for Surfer, as he'd been the one working as an advance scout for Galactus, finding planets for his master to munch on. More importantly, it would establish the Fantastic Four as adventurers and set both them and the Surfer up for the more cosmic Phase 4 to come.
Acts of Vengeance 
This was a pretty simple, early crossover event, but one that would translate very well into an action flick. Loki emerges as the mastermind behind a plot where super-villains team up and attempt to take down their greatest foes by mixing things up. Rather than fight the Fantastic Four, for example, Doctor Doom would take on the X-Men, while Magneto might take on Captain America. Predictably, the plan fell apart when the villains started fighting with one another, particularly concentration-camp survivor Magneto and uber-Nazi Red Skull.
Onslaught Saga 
A new entity created from the combined consciousness of Professor Xavier and Magneto, Onslaught was the result of Xavier shutting down Magneto's mind, effectively absorbing it into his own. He did this in response to Magneto ripping the adamantium out of Wolverine. The only way to stop him was for the non-mutant heroes facing him (that would be the Avengers and FF) had to literally fly into his energy form. This seemingly destroyed Onslaught and the heroes, but the latter were "Reborn" on a new world in a pocket universe where they spent a year before returning to the Marvel Universe. This would present one way to cast younger versions of some of the classic Avengers characters so the MCU can move forward.
With the Fantastic Four comes the Negative Zone and it's bug-like ruler Annihilus. Amassing his forces, Annihilus launches the Annihilation Wave into the Marvel Universe proper. His first move is to wipe out the Nova Corps (seen in "Guardians of the Galaxy"), who had convened for a special meeting, save the Earth representative Richard Rider. Seeking the elimination of all life in the universe. Annihilus manages to make a weapon out of Galactus and seems nigh unstoppable, but his "weapon" would prove his undoing. This is a great story for the cosmic expansion of the MCU, creating a new hero in Nova with established connections to the Guardians.
Secret Invasion 
Another recasting opportunity, this is the ultimate in Marvel paranoia. The premise is that the shape-shifting Skrulls have been infiltrating the Marvel Universe for years, replacing key characters including superheroes, villains, politicians and corporate leaders. When their plans are revealed by the death of one of their own (Elektra) -- who reverts back to Skrull form -- the invasion plan has to move forward in a hurry. Everyone was a suspect with heroes and villains having to join forces before the Skrulls could finally be defeated. Then, it was revealed that the people who had been replaced by Skrull invaders were still alive, held in stasis all that time. That means if they took Tony Stark when he was in his 20s, you could recast a younger actor and move on with a new-old Tony Stark still a fixture in the MCU.
Dark Reign 
Following the events of "Secret Invasion," Norman Osborn leveraged his role in the defeat of the Skrulls into becoming head of S.H.I.E.L.D. He disbanded the Avengers and formed his own team of "reformed" villains who'd also helped in the battle. He worked behind the scenes with other super-villains to gain even further influence and power, all the while playing the hero Iron Patriot to the public. The real heroes had no choice but to work in secret themselves to undermine his power and try to expose his true agenda so they could take him down without facing arrest or incarceration themselves by the world's leading peacekeeping force Osborn controlled.
Avengers vs. X-Men 
With the Phoenix Force heading to Earth, Cable emerges from the future to reveal that The Avengers are to blame for the extinction of mutantkind and the decimation of the future. The Force is seeking Hope Summers, the last mutant at this point, but winds up in five different mutants when Hope is hidden from it. They proceed to capture and decimate the Avengers forces, offering up classic battles between key X-Men and Avengers -- fan service at its finest. Ultimately, Scarlet Witch brought Hope to take on the Phoenix force and restore the mutant population.
Uncanny Avengers 
Speaking of fan service and spinning out of "AvX," Captain America realizes he hasn't done enough to help the X-Men in their struggles for acceptance "in a world that fears and hates them." So he comes up with the Avengers Unity Squad, made up of members from both the X-Men and the Avengers. Logically speaking, this is just the obvious direction a merged Disney-Fox Marvel has to be heading. Fans have been waiting more than ten years to see some of these characters interact, and this is the most logical way to make that happen.
Red Skull gained the powers of Charles Xavier and Onslaught, making him the ultimate evil. The key element of this storyline was an "inversion" spell gone wrong. Intended to revert Red Skull back to normal, it instead flipped the good and evil of several heroes and villains, including Captain America, Sabretooth, Carnage, Iron Man, and Doctor Doom. By the end of the story, most of the characters had been reverted back to their original state, but it would be a fun way to create new heroes and villains from familiar faces.
Secret Wars 
Tapping into the idea of parallel realities, this event merges a ton of established alternate Marvel Universes into one Battleworld under the rule of Doctor Doom, with the veritable powers of a God. The Thing serves as a wall between the more dangerous zones, like the Annihilation Wave and Marvel Zombies, while other members of the Fantastic Four have key roles as well. Doom created Battleworld to salvage what he could as the multiverse collapsed, but his greed overcame him and he set himself up as its rulers. It takes the combined might of various alternate heroes to take him down and establish a new Marvel Universe. Recasting? This is the story that brought Miles Morales (Ultimate Spider-Man) to the main Marvel Universe. nudge nudge wink wink
Inhumans vs X-Men 
The Inhumans work best as side characters, and this is one of their best storylines. After an earlier event caused their sacred Terrigen Mist to be dispersed into traveling clouds on the Earth's surface, it is learned that while Terrigen is the heart of the metamorphasis that creates new Inhumans, it is also lethal to mutants. As all of the Terrigen is in these clouds, and it is sacred to the Inhumans, a complex situation was created that pitted these two powered groups against one another to deadly consequences. This could be the story that would finally get fans excited about the Inhumans.
Weapons of Mutant Destruction 
The Weapon X Project is where Wolverine and Sabretooth came from, among other mutants, but a recent storyline saw the covert organization developing something even worse. They merged the DNA of their existing Weapon X cadre of characters with that of Bruce Banner aka the Hulk, creating a new and even more dangerous hybrid dubbed Weapon H. A brand new character, picture the Hulk with Wolverine's healing ability -- like he needed the help -- and adamantium claws. While his story is still unfolding in the comics, fans have embraced this unique combination of two fan-favorites, even as the Weapon X mutants have come together to shut down the Weapon X Project for good.
BONUS: Deadpool Kills the Marvel Universe
In comic books, Deadpool has done this twice now in completely disconnected series, but that gives filmmakers two options to choose from. They could come up with a whole new story, too, obviously. It doesn't really matter as it's totally out of continuity with its tongue planted firmly in its cheek, offering twisted, dark humor and plenty of gory violence. This could cameo everyone and anyone from the MCU willing to die a horrific death on-screen ... just for fun. Honestly, Ryan Reynolds is probably already working on the story for this.