this reminds me of when they killed off Optimus Prime in TF the movie, Hasbro killed off several major characters in the film to make way for new toys. and that seems to be the same reason for making Twilight an alicorn, to sell A new toy line.(as suggested by those leaked tweets) as it stands right now, it's permanent. Twilight Sparkle is an alicorn princess. looking back at what happened in transformers, Hasbro resurrected prime after fan outrage. so if enough of us bitch to hasbro, maybe......only time will tell.