@Timstuff
And have people give up on the concept of Molestia? Are you loco in the coco?

Actually, the inherent immortality of alicorns is frequently brought into question by the fact that Cadance appears to have aged at a normal rate compared to Twilight and Shining Armor.

Faust had originally intended Luna and Molestia to be the only alicorns, but it's not out of the realm of reason that they are the only immortals.