The X-Men are already part of the Marvel Cinematic Universe
Now that we are done with MCU Phase 3, and some of our favourite Avengers are retiring, we can expect Marvel to bring X-Men into the mix anytime soon. A fan theory claims that the snap in the last two movies opened up a lot of energy, and the potential of the X gene getting activated in the same universe.
Fantastic Four will be the new owners of the Avengers Tower
Now that the Avengers have been dismantled, the Avengers Tower is much talked about topic in the MCU. Some fans theorise Fantastic Four are set to come into the MCU, and they will take over the Avengers Tower, renaming it Baxter Building. Exciting!
Yelena as the 'next' Black Widow
Now this one could be true. We all know Black Widow, or Natasha Romanoff, sacrificed her life in Avengers: Endgame. But, with Black Widow coming this summer, her long lost sister/friend Yelena could be the one carrying her mantle, with a similar skill set.
Peggy Carter is Tony Stark's mother
Okay, brace yourselves. So, Peggy Carter was Steve Rogers' love interest back in the day. But after Rogers presumably died, and everyone mourned him, the camraderie of Carter and Howard Stark was pretty decent. Who knows they ended up together, and Tony Stark was their son. Just saying.
Ant-Man has been there since the beginning
Ant-Man was first seen in 2015's origin story, but who knows whether he was there even during the Battle of New York? He obviously has the ability to convert into a microscopic form factor, so he might as well have been helping the others.
Nick Fury is actually Jules Winfield
Samuel L Jackson is popular for his role of Jules Winfield in Quentin Tarantino's Pulp Fiction. A lot of hints indicate Nick Fury might just be the same. At least fans are begging for a Tarantino X Marvel crossover.
Doctor Strange 2 will show the misuse of Time Stone
Doctor Strange in the Multiverse of Madness is the sequel to the super popular origin story. Billed to be a horror movie, Doctor Strange 2 might just be a film that shows how the Time Stone gets into the wrong hands, possibly even reversing some good actions in the MCU.
Bucky killed Peter Parker's parents too
This one is disheartening. We all know The Winter Soldier killed Tony Stark's parents, albeit in a controlled state of mind. However, a new fan theory suggests he might have killed Peter Parker's parents too, considering we don't get to see them ever in the MCU.