I definitely believe there are 3 "worlds," maybe not in the sense that others are interpreting, idk.
Clouds "world" is where we played through in remake, and will moving forward.
Zack's is actually the lifestream (I still believe he is dead)
Sephiroth's is one where both are destroyed.
I think the Edge of Creation was Sephiroth partially telling Cloud his plan but still misleading him. It really seems like SE is leaning in hard in showing how much Sephiroth is gaslighting Cloud. At least from my perspective based on my experience of what we've seen so far, and my knowledge of the compilation.
I'm definitely open to being wrong, but this is where I'm still at with the Remake project.
It has been officially confirmed he's alive... for now.