User blog comment:IceFireWarden0/Next Official Elder Scroll's Game Predictions/@comment-142.1.57.140-20121129183607/@comment-124.180.178.4-20121202052531

The purpose of Alduin from what I gathered is to usher in new Kalpas, by pretty much om-nomming the Aurbis (or atleast Mundus). Then I guess he regurgitates it or something. He is called World-Eater because that is literally what he is meant to do.

By the way, the only purpose Nirn has for the Daedric Princes is entertainment.