If you'll allow me to sidetrack for a moment, I've kind of been wondering about the Princess and other royalty being alicorns. (All of you will just have to excuse me using that word. I really don't know what else to call them, and mash-up words like unisus just plain look dorky to me.) In Japanese folklore kitsunes, magical nine-tailed foxes, start out as regular foxes, but as they learn more magic, their lifetime extends. Once they reach the age of 100, they grow a new tail, like they will from then on every hundred years, until at the age of one thousand years they have nine tails, and are truly immortal. Perhaps the condition of being an alicorn is similar. They might well start as normal unicorns (since they seem to have a natural affinity to magic) and at some point, they reach a level of power where their magical ability manifests as wings, or other ways (like Celestia's eternally flowing mane).