A Reddit theory by user accountfornerdstuff puts the permanency of Thanos's snap into question. The theory is that rather than snapping half of the universe out of existence, he snaps them to a parallel universe. The MCU has touched on alternate universes in Doctor Strange, and in Ant-Man, we visit the Quantum Realm where time and space become irrelevant. Reddit user Accountfornerdstuff theorizes that Ant-Man and the Wasp will discover doorways to alternate universes in the Quantum Realm and lead the remaining Avengers to a universe where either Loki's attack on New York hasn't happened or is happening, allowing them to grab the Space and Mind Stones. They can use their knowledge to find the other Infinity Stones, create their own gauntlet, and take on Thanos. Check out the full theory here!