Man, I was wondering if I was the only person who thought this. Yes it seems like all princesses are alicorns but we don't know if that was how Faust originally designed it. It seems far more plausible to me that Hasbro took Faust's original idea about succession and turned it into a toy opportunity.

My headcanon has always been that alicorns are born, not made. It's genetic. In lieu of actual daughters, Celestia could have groomed Twilight for the job regardless of "type" (what's the official term for that? is it just "type"?) - of course there's Cadance but she wasn't originally an alicorn either, huh?

idk man.