Well that's only half accurate. We know that if the DO wins, there WON'T be a universe at all (it was made very clear).
As for if he dies - that doesn't explain anything at all about who is locked. He could die and the people can remain trapped in their prison.
I have a theory I wanted to share with you guys, bare with me here.
We know that time in Randland is circular, repeating time and again. We know that each turning, a bore is drilled outside the wheel into the DO's "prison," and all hell breaks loose.
However, we also know that the DO...