Leave It Alone
The best solution is for Marvel Studios to just leave the Avengers franchise alone for as long as possible (if not until a reboot). After Avengers: Endgame, how could the studio possibly top it? It’s a history-maker and part of cinematic legend. Heck, you could argue that it’s even bigger than Star Wars and has become this generation’s “it” franchise.
That should come with immense caution, though. Looking at Star Wars, Marvel Studios should take note of how it can all go south in an instant. Everyone thought that the franchise was immune to absolutely anything, but Solo: A Star Wars Story‘s box office failure was an unwelcome reminder of how fan rebellion can happen when you upset the bulk of the fanbase with a few unfavorable decisions. Let it be a lesson that fans aren’t merely piggybanks for studios; they can make or break something if they choose.
With that said, there’s really no need for another Avengers movie after Avengers: Endgame. By all means, cherish it and the memories, but let’s move on.