Ah..... I don't particularly care for Twi becoming an alicorn. But, looking at the commercial, could it not be Cadence that the coronation is for? She hasn't actually had a princess coronation, if you want to be technical about it. It is more likely that Twi is the princess, though. Fluttershy says, "You look just 'like' a princess.". Cadence already looks like a princess. Oh, well. Trust the writers, I guess. I'm not too happy about it myself.