Given what we've seen I do not rule out that he could potentially be as powerful as the DO.

The Essenes of Mashadar you speak of was potent enough to effectively destroy the taint and the wound in Rand's side is just as potent as the ne inflicted by the evil of S'T ... Also if the DO dies Rand will not have to rebuild his prison, he needs to create a new one... I'm not saying I think this is how it will pan out ... Merely something I would not be surprised by.