I believe she said that 2 "main" characters would buy it.
I think that Voldemort is probably one. But that leaves the other open. I think our main characters are: Harry, Ron, Hermione, Ginny (
maybe), Hagrid, Snape and possibly Draco Malfoy.
Once you get past the first three, it enters very quickly into opinion, and after Malfoy, the ice gets very thin, indeed.
As far as who else goes, she's hinted that Harry might not ever make it to full adult-hood (someone asked her what he'd be like as an old man and she responded with something to the effect of "what makes you think he'll live that long?"). If she doesn't kill off Harry, I'd say Snape, Malfoy, and Hagrid are good candidates. I really don't think she'll bump off Ron or Hermione, they've clearly (to me) been planned to marry and grow old together from the very first novel. I also think that Ginny is probably safe, but who knows?
I'm currently re-reading them, and looking for death foreshadowings for Snape and Harry, but I'm in HP3 at the moment, which is
all death foreshadowings for Harry, so ....