Age spells · 7:52am Nov 12th, 2015
A lot of fictions concentrates on the fact that alicorns are (or, at least, seem to be) immortal.
I am not entirely convinced that they indeed are, but setting aside arguments that Celestia and Luna are rather exceptional even by alicorn standards, I would like to note that a lot of people simply forget the age spells that Trixie performed with her alicorn amulet.
Granted, it was something only a "Highest level unicorn can do" but apparently those things are not unheard of, and they do indeed make a target at least a decade younger. So even without becoming an alicorn, some exceptional ponies, that can either cast the spell themselves or afford to get someone to cast it on them would have a good chance at the unnaturally long lives even without becoming Princes/Princesses.