Avengers Endgame is one of the biggest achievements in cinematic history, and Marvel did a pretty stellar job of making sure the film lived up to expectations.
It did a spectacular job of drawing to a close an era of cinema that has defined popular culture for the last decade.

We can’t even begin to imagine the process that goes into creating such an insane production, so it comes as no surprise that we shouldn’t be expecting something of that size again any time soon.
Discussing Marvel’s process in an interview with ComicBook, producer Trinh Tran explained it could be another decade before we get something of Infinity War and Endgame level again.

“Our focus right now is to make sure that the titles that we’ve released in Phase 4… obviously those stories are going to be new, exciting, different and can connect with the audience like the other movies have been.
“Over 10 years ago, it’s always been our dream to get to Infinity War and Endgame level. We didn’t know obviously where that was going to go at the start of the studio, but it’s incredible to know that we were able to accomplish that.”

“Now it’d be amazing if we could get to that level 10 years later, so I think it’s a dream to continue doing that and build upon the MCU and the connective tissue that we have,” Trinh further noted.
“And now with obviously our Disney+ [the streaming service] side and the shows and how our characters are venturing into that world and how that’s gonna lead to the future and more franchises and more stories and more properties and their connective tissue to the rest of the MCU, it would be amazing to do something like this 10 years later.”

It’s quite a sad thought really, though it’s more than understandable.