I don't remember too much, but an important detail of the film was that Santa was supposed to a human who houses the Spirit of Christmas, rather than being an immortal saint. Santa literally becomes the embodiment of Christmas. The death of Santa would mean the death of Christmas.
As the current Santa is reaching the end of his life, the business suits of the North Pole decide on the next man to have the Spirit passed down to. This is done with a special box that is opened only to the retiring Santa, who then whispers the words he sees in the box to his replacement. The Spirit is then magically passed down. The suits take the aged and retiring Santa to a mall, where their chosen candidate is, but then a man who was trying to steal a teddy bear for his daughter ends up inheriting the Spirit of Christmas instead.
As the current Santa is reaching the end of his life, the business suits of the North Pole decide on the next man to have the Spirit passed down to. This is done with a special box that is opened only to the retiring Santa, who then whispers the words he sees in the box to his replacement. The Spirit is then magically passed down. The suits take the aged and retiring Santa to a mall, where their chosen candidate is, but then a man who was trying to steal a teddy bear for his daughter ends up inheriting the Spirit of Christmas instead.