One of the biggest questions left by Avengers: Endgame was, well what the heck was Captain America doing the whole time if he went back in time to return the stones and eventually stayed to live out his entire life? Directors Joe and Anthony Russo have previously attempted to explain it by saying when Captain America left he entered a "branch reality" as a means of trying to explain it in post-release interviews. Speaking in a new talk with the Lights Camera Barstool podcast the pair were asked if they had any idea what took place while he existed in that reality, with Joe Russo simply saying: "Nope, no idea."
He elaborated further, trying to explain the concept again, saying: "One thing that's clear that Anthony and I have discussed, I don't know that I've discussed this publicly at all, Cap would have have to traveled back to the main time line, that is something that yes he would have been in a branch reality but he would have to travel back to the main timeline to give that shield to Sam Wilson...In our internal logic that we defined in the room, that was the choice that we made was based on everything that happened he would have been in a branch reality and then had to have shifted over to this so jumped from one to the other and handed the shield off."
As to why this wasn't explored in the movie and where things went from there, Anthony Russo added that working on Endgame was freeing for them because they didn't have to worry about that part of the storytelling anymore.
"One of the great thrills of doing Endgame though was at that point we had worked with Markus and McFeely for four films telling a continuous narrative," Anthony Russo said. "I can't tell you how liberating it was to be able to finish and deliver Endgame without any idea or any thought about how it moves forward from there. Because up until that point it was always about how do we move forward, how do we move forward, and it was very creatively liberating to not have that burden any longer."
The Russos may not have had to worry about what happens after Avengers: Endgame, but Kevin Feige certainly had to and has enough ideas that the MCU is mapped out until at least 2028 which will hopefully feature at least the next Avengers movie.