Board Thread:Lore Discussion/@comment-26861588-20150814151511/@comment-6881629-20150814183233

The book Varieties of Faith in the Empire says -

"Alduin's sobriquet, 'the world eater', comes from myths that depict him as the horrible, ravaging firestorm that destroyed the last world to begin this one."

Thats the closest thing to a explanation of how Alduin would end the world i can think of thats in the game.