Then there’s Into the Spider-Verse, the Oscar-winning animated film that also featured the idea.
Interestingly enough, on the DC side of things, something like this is already set to happen.
In the standalone Flash film starring Ezra Miller, Michael Keaton and Ben Affleck have both signed on to appear in the film as their respective versions of Batman, as Flash’s super speed presumably opens the way to alternate universes.
Marvel fans are now betting the MCU is reaching for something similar.