Okay, quick theory.

The writers have said that those dead are going to stay dead. I think probably they’re trying to to word things carefully so that what they really mean is: “Characters who are ACTUALLY dead at the end will stay dead”, and we’ll learn that the dusted Avengers are still alive, so they were never technically lying. But it did get me thinking.

So if they do really mean the dusted Avengers are for sure dead and will stay dead, while also accepting there’s no possible way they are permanently killing off Spidey, Black Panther, and Strange there’s really only one solution I can think of:

What if, in an alternate universe, the Avengers that got turned to ash in our reality are the ones that survived, and those that lived got turned to ash?

And, ultimately, the way to “fix” what happened is to merge the two realities? That would mean the “original” Avengers we knew are dead and stay dead, but we still have these characters going forward.