Board Thread:Lore Discussion/@comment-16473632-20150305113038/@comment-1600847-20150305113520

Either a) he was taken into the Deadlands during the Oblivion Crisis, or b) that was a rumor. Either way, he explains to you in Morrowind that after destroying the Heart of Lorkhan he will no longer be a God, he'll become mortal again. Still a very powerful being, but mortal.