War Oh dear God. I just thought of something worse. If he became a vampire, he could live indefinitely, since, as far as I'm aware, vampires can't die of natural means. And if he also can't be killed, then that means he could never die. Ever.
As a side note, I went into the lore to find out how old Serana of Volkihar is, and it turns out she's between 5050 years old and 4207 years old, more likely leaning towards the older end. As in, she was probably born in the Merethic Era. And compared to some other vampires, she's young. So it seems like vampires either do live indefinitely or just for several thousand years. No big deal.