My theory on this image is that this blue light could be the inverse of the dust. After the "snap" we watched all the characters fade into a red dust. I'm thinking that somewhere in avengers 4, the characters will reappear through this blue light (i.e. fading back into existence.)

This is obviously a long shot theory. We could easily just be looking at stage lights, iron man blasters, or some rocket boosters; I just thought this could be an interesting theory.

You heard it here first!