I think it’s a given that one of the characters who dies has to be Voldemort. Rowling says “there has to be a price,” though, so I take that to mean that one of the other major characters will have to be a sacrifice. That could mean either a “good” character (Ron, Hermione, Harry, Hagrid, Neville?) or a “bad” character who redeems himself (Snape, Malfoy?).
I get a little bit of a sense from reading the article that she may not have quite decided yet but that she isn’t ruling anybody out at this point.
I don’t take her suggestion that Harry might be the one to go very seriously, though. If she wrote the final chapter in 1990, I can’t believe Harry’s fate would not have already been mentioned in it. I think she’s probably just being coy and doesn’t want the audience to think that anybody is safe.
My personal WAG is that there will be a redemptive sacrifice by Snape.