Avengers: Endgame ended with Steve Rogers travelling back in time to return the Infinity Stones and Mjolnir to their rightful place in the timeline.
While we believe that Captain America made good on his promise to do that, we also know he decided to remain in the past for a reunion with Peggy Carter. Later, he was shown in the present day as an old man, handing his shield and the Captain America mantle to Sam Wilson (after watching Loki and learning about branded timelines, it's a moment that has left fans with more questions than answers).
The first Avengers: Doomsday teaser picked up with Steve in the house he shares with Peggy and their child. It's widely believed that his newfound family life will be interrupted by Doctor Doom, after Cap's actions caused irreparable damage to the Multiverse.
Reuniting with Peggy changed history, but might Steve have found himself—or even created—an alternate timeline?
While not confirmed, multiple social media "scooper" accounts, including @MyTimeToShineH, are claiming that Steve and Peggy are on Earth-828. That's the home of the Fantastic Four, and could explain rumours that Chris Evans shot a post-credits scene for The Fantastic Four: First Steps that ultimately wasn't used.
When that claim first surfaced, it was reported that Steve would cameo as "Nomad," a persona it's since been reported he'll take on in Avengers: Doomsday (where he'll allegedly rock a beard and wield Mjolnir).
Cap being on Earth-828 raises some big questions. Did his presence there create a butterfly effect that led to the creation of the Fantastic Four, for example? Don't forget, we've heard that Evans and a child actor shot scenes in a 1960s-era baseball stadium, which could easily be mistaken for the restrofuturistic world Marvel's First Family calls home.
We'll have to wait and see, but all of this ties into what we've heard about Steve and Doom possibly being on that rocket ship alongside the Fantastic Four...
Avengers: Doomsday officially stars Chris Evans, Chris Hemsworth, Anthony Mackie, Winston Duke, Tom Hiddleston, Sebastian Stan, Letitia Wright, Paul Rudd, and Robert Downey Jr. Wyatt Russell, Simu Liu, Tenoch Huerta Mejia, Mabel Cadena, Florence Pugh, Danny Ramirez, David Harbour, Hannah John-Kamen, Lewis Pullman, and India Rose Hemsworth all make their Avengers franchise debuts.
The Fantastic Four: First Steps leads Pedro Pascal, Vanessa Kirby, Ebon Moss-Bachrach, and Joseph Quinn join them, as do X-Men franchise stars Kelsey Grammer, Patrick Stewart, Ian McKellen, Alan Cumming, Rebecca Romijn, James Marsden, with Deadpool & Wolverine star Channing Tatum. The trades have pointed to Ryan Reynolds and Hayley Atwell also appearing in Avengers: Doomsday.
The Russo Brothers direct Avengers: Doomsday and Avengers: Secret Wars from a screenplay by Stephen McFeely, with whom they previously collaborated on the Avengers and Captain America franchises. Loki and Doctor Strange in the Multiverse of Madness's Michael Waldron has also been enlisted to help refine the story.
Avengers: Doomsday is set to be released on December 18, with Avengers: Secret Wars scheduled to arrive on December 17, 2027.