Warning: This post contains theories, speculation, and potential spoilers for Avengers: Endgame.
The Spider-Man: Far From Home trailer, featuring Peter Parker in the flesh and not as a bag of dust, confirms what we've expected from the moment it happened - Thanos's Snap will not be permanent. The question has never really been "if" the Avengers will bring back half of the universe, it's "how." How will Earth's mightiest heroes deal with the Great Dusting in Endgame? Here are five ways they might, and when, and what each would mean for the MCU.
Stopping It Years Earlier
The Mad Titan's hunt for the Infinity Stones started long before Infinity War, during a time when the Avengers and Guardians briefly possessed various stones themselves. Rather than try to stop an overpowered Thanos after he already has a couple, like in Infinity War's first scene, the best way to prevent the Snapture might be to go back years earlier, possibly when the Avengers had them. That idea fits with the theory saying Doctor Strange locked everyone into a time loop going back to at least Age of Ultron.
The ramifications of this would be huge, though. It could alter everything that happened in the MCU, a butterfly effect for the whole franchise.
Stopping Thanos Right Before the Snap
If the Avengers (and Marvel) want to avoid retconning/erasing/altering years of movies, stories, and character development, they could have the Avengers stop the Snap moments before it happened. That would mean everything we saw up to and including the majority of Infinity War will still have happened. This approach would also make sense in the fictional world, where the Avengers would not want to unnecessarily change the past too much, to avoid huge, unintended consequences.And if their goal is to change the timeline as little as possible, the safest option would be to do it as close to the Snap as they can. That has the potential to give fans the most satisfying outcome of all, when a wiser Thor knows to aim for the head. (The tingle you're feeling after reading that sentence is natural.)
They Reverse It Immediately
Doctor Strange "let" Thanos win, but that must have been his only option, since he foresaw the one timeline where the Avengers prove victorious. If letting the Snap happen in the first place was necessary, it might be a bad idea to stop it entirely. But what if their time traveling capers and trips to different dimensions let the Avengers amass their own collection of Infinity Stones?Before the dust settled on Thanos's universe-halving, the Avengers could use their own Gauntlet to snap his victims back into flesh. Unfortunately that might only be possible if they all pay the ultimate price.
They Reverse It Later
Infinity War ended with a contented Thanos watching the sun set on a grateful universe, his "destiny" fulfilled. But as the old saying goes, "pigs get fat, hogs get slaughtered." Being done with his life's work might make Thanos unfocused and vulnerable. Plus his children are all gone, he's the universe's greatest monster, and no one fighting him has anything to lose. A regrouped, refocused, Captain-Marvel aided Avengers might be able to defeat him later.They could then use the Infinity Stones he collected to bring everyone back after some time has passed.
They Don't Stop or Reverse the Snap (But Still Bring Everyone Back)
After the Snap, Thanos traveled into the Soul Stone, where young Gamora was waiting. Red Skull said the Soul Stone has "a certain wisdom," though we don't know exactly what that means yet. What if all of Thanos' victims aren't gone, just in the stone, where it is protecting them from a madman? If they're "trapped" inside of it, that means they can be released from it, and the Avengers don't have to avert or undo the Snap at all, they'd just need access to the Soul Stone.But if Thanos had to sacrifice Gamora just to get it, what price would the Avengers have to pay to free trillions of lives from the soul stone?
Forget how the Avengers will deal with the Snap, the real question is how are we emotionally going to deal with Endgame?