My theory is that "Mr. Saidoutbitch" will become a good person, deserving of Heaven, but get offed by a thief. In Heaven, he hears what happened to Lucifer, the only person who ever gave him a chance to be more than a thief, and volunteers to take his place in Hell. God grants his wish and turns him into an Angel, so he can take the Throne of Hell.

Some foreshadowing that fits this (they could be planning this far ahead, the show writers are brilliant) LUCIFER SENT HIM OFF WITH A CROWN ON HIS HEAD! Ergo, the new King of Hell!