It’s obviously not Regina. It would be too obvious and they’ve already showed her “dream” in the promo so there’d be no surprise if she died. Regina is a complex character with a tragic past and I’m a sucker for those kinds of characters. Season 2 without her wouldn’t make sense to me.
Rumpel… well, maybe.
Emma or Henry – Definitely not. Emma is the main character and killing off the hero would be dumb (although I find Emma a bit boring). And Henry is part of Emma’s happy ending. Could be Henry, yes, but then Emma would spend the whole next season seeking revenge and that is not what the show is about.
Snow or Prince – That would ruin the show since 80% of the audience loves and expects them to have their happy ending. I don’t think they’re willing to risk losing so many viewers.
Or maybe this is just E! fooling us. Wouldn’t be the first time.