Avengers: Endgame - 9 Possibilities For The Secret New Post-Credits Scene
6. It's A Gag Ending (They HAVE Done It Before)
The cynics out there will say that the only reason Marvel are re-releasing Endgame is because they've come so close to beating Avatar for the highest grossing film of all time record and are going to miss out. What better way to beat James Cameron's behemoth champion than by repeating his own trick and putting it back in cinemas with a cursory reason to entice fans back in.
It could well be that the only new footage in this repackaged Endgame bundle is something like the Shawarma scene that was tacked onto the end of The Avengers for a bit of cheap fan-baiting. It added absolutely nothing to the movie, but it was fun and it establishes precedent for Marvel to go back and do similar. And it's not like they haven't used post-credits scenes solely as gags in the past...
Even if Marvel do this, they could claim that they're sending Endgame back to cinemas as a prologue reminder for Far From Home, because the plots are so tied together. That'd be a clever excuse, of course, but it wouldn't stop questions of why they didn't do the same for Infinity War if this is genuinely their only wholesome reason.