Spoiler Thread: Avengers Infinity War

Thanos said that they would cease to exist, I'm not sure that means they never existed.

When he stabbed Tony Stark he said "You've earned my respect, Stark. When I'm done, half of humanity will still exist. I hope they remember you."

Based on that statement and some of the Avengers 4 set photos I think we are going to see a world where the people that dusted never existed. I went in depth into the theory earlier in the thread.