Let's all take a break from Star Wars mania to remember that Disney has just acquired 21st Century Fox, in a major deal that will allow the X-Men and Fantastic Four franchises to join the Marvel Cinematic Universe. Of course, the first hurdle to get over is the process of how the X-Men and F4 can be brought into the MCU.
Fans have their own working theories (including our own "Heroes Reborn" option), but one of the biggest theories has been that the upcoming X-Men: Dark Phoenix could be refitted to serve as a back door introduction of Fox's Marvel characters into the MCU.
Read on below for a breakdown of how the final installment of Fox's X-Men franchise could be the bridge to a new beginning at Marvel Studios.
The primary reason for Dark Phoenix being looked at as the gateway for an entire change in universe is that it's something that's happened in the comics before. Dark Phoenix is linked to a reality-altering artifact called The M'Kraan Crystal, which is also known as "The Nexus of Realities." It allows user to travel between any universe of the multiverse, while its designated protector (often The Phoenix Force) exists as a constant and anchor across all realities.
Right now, there's no way to know if X-Men: Dark Phoenix will follow the "Dark Phoenix Saga" of Marvel Comics, making the M'Kraan Crystal the major MacGuffin of the story. However, it wouldn't be too hard to go back and add the crystal to the film's storyline, even as an epilogue or post-credits scene.
Depending on what happens in the film, Jean Grey / Phoenix could find herself connected to the M'Kraan Crystal, suddenly aware of all the universes that are out there - including the Marvel Cinematic Universe.
The X-Men movie timeline has already gone through one reboot, where the events of the original trilogy have been negated by the historical manipulations of Days of the Future Past, creating one timeline where films like The Wolverine and Logan take place, and a secondary one that is still being explored in films like X-Men: Apocalypse and Dark Phoenix. Since the X-Men movies have already established big changes like altered timelines as a possibility, it shouldn't be too hard to do it again.
Fox and Marvel have all the leeway in the world right now to use the the story of The Phoenix (with or without the M'Kraan Crystal) as a vehicle for burning down one reality and establishing a new one. Given the level of tragedy and sacrifice that have been a part of Fox's X-Men movie saga (not to mention the possible dark futures ), it would be something of a mercy gift if Phoenix were to see a reality like the Marvel Cinematic Universe and transport the X-Men there, to a world that's arguably lighter and full of more hope for mutants to be looked at as heroes.
In the end, it seems like a simple revision of the finale of X-Men: Dark Phoenix would be a decisive and relatively painless way to bring Fox's X-Men movie saga to a close, and open a pathway for a dimensional retcon that finally introduces mutants to the MCU. With Avengers: Infinity War set to explore the idea of an artifact that can open doorways between entire realities (the Infinity Gauntlet), it's change that could be explained easily from either side.
The X-Men film universe continues with The New Mutants on April 13th; Untitled Deadpool Sequel on June 1st; and X-Men: Dark Phoenix on November 2nd. Avengers: Infinity War opens in theaters on May 4, 2018. Thor: Ragnarok is now playing in theaters. Other upcoming Marvel Cinematic Universe movies include Black Panther on February 16, 2018, Ant-Man and the Wasp on July 6, 2018, Captain Marvel on March 8, 2019, the fourth Avengers movie on May 3, 2019, the sequel to Spider-Man: Homecoming on July 5, 2019, and Guardians of the Galaxy Vol. 3 in 2020.