Get ready for a deep one that we didn't expect either. Ernest Saves Christmas (1988) and The Santa Clause (1994) are two of the most accurate retellings of the Holly King and Oak King, in which Father Christmas dies, loses his magic or otherwise retires, a new younger king replaces him. Also described in much more detail in Frazer's The Golden Bough - specifically Chapter VIII titled "The Killing of the Tree-Spirit" which itself is just another of Frazer's many examples of the "Killing the Divine King" ritual.