I didn't read the Onslaught sage, but from what I understand, he killed the Fantastic Four and the Avengers and a lot of other heroes. Franklin made this Heroes Reborn Universe, so is that Earth-616 as we know it now, or is it something else?

He didn't kill them I think. Franklin like made a place for them just incase they were ever needed again. However they had no ideas of what happen and onslaught was a totally new threat to them. Its confusing I gotta reread it again.

onslaught killed the fantastic four and the avengers, franklin made a pocket universe with all those heroes in it. the pocket universe is the size of a basketball with a entire universe in it. earth 616 is the same way it was nothing happened to it.

I dispute that Franklin created the pocket universe..............

Nate: "im supposed to trust you? look around this is you"

Onslaught/Xavier: "there is a world that will accept you. Its small but its there. I dreamt it and I BUILT it".

This is right before Onslaughts defeat, right before Nate/Franklins escape and right before the creation of the pocket universe.

http://picsorban.com/upload/xavier creates blue ball2.jpg

well in the comics it says how he built it, and the celestials knew he built it thats why they wanted him