Rescuers: Endgame Theories involve quantum realms, time loops, time spells, numerous dimensions, competing chronologies that have been decimated by decades of comic books. Marvel intends to solve Thanos snap in a way that actually makes sense to visitors who are not super-good.
The recently posted post on Reddit may be the most galaxy brain. It’s long and confusing and involves math.
A number of people have presented fan theories about what Avengers 4: Endgame will be.