What's nice about keeping Endgame as the "end" is that that's exactly how it was written. Christopher Markus and Stephen McFeely said that Feige allowed them to write the finale with no thought on how things would continue afterward. No setups for spinoffs or teases for future sequels in the movie or after the credits. Just a true finale to the entirety of the MCU, everyone signs their names, does a last curtain call, the end.