Because this discussion is going all metaphysical and faithy, I've got to point out this interesting little question : Did Kripke indicate Dean was needed to do God's work way back in Season One, with the episode Faith?


See, Roy the preacher man, didn't know his wife had caught and bound that Reaper, and that the Reaper was trading a life for a life. So if you go on the assumption that Roy was a true believer, and that maybe God took double advantage of the situation - save Dean, stop the evil - then God told Roy that Dean had more work to do.

I haven't had a chance to watch Faith, HotH, Mystery Spot and Lazarus back to back, but I don't think Faith should be discounted when one contemplated God's plan for Dean.