:LOL:
It's pretty simple. That quote plus the Avengers 4 set photos that show Stark in a SHIELD outfit during the Battle of New York and other scenes from around that time slightly changed. I also have a theory that some of the scenes in the trailer that weren't in the movie like Hulk at the Wakanda battle are actually from Avengers 4.
My theory is that Antman is not affected by everyone being erased. My guess is he's in the quantum realm when Thanos does the finger snap. The early part of Avengers 4 is Antman trying to convince the Avengers of what happened.
Obviously, it's just all speculation, but it's damn good speculation. ;)