The Avengers: Endgame theory starts off by stating that the dusted heroes, along with half of the universe, are all dead.
An interesting Avengers: Endgame fan theory introduces the Mandela Effect into the Marvel Cinematic Universe.
While we wait, you can head over to Reddit to read the original Avengers: Endgame fan theory.
It all starts with the 14,000,065 potential futures that Doctor Strange saw in Infinity War and it will introduce alternate timelines to rescue the Decimated heroes.