Harry? No. It's his series and he has to kill Voldemort. He's destined to be a great auror. She could kill off Harry, but the fans wouldn't like. Granted, she's already the richest women in England and she'll be done anyway, so it's possible. But not likely.
Hermione: she's Rowling alter ego. She gets to live and prove that mudbloods are wizards, too.
Ron: No, unless he realizes that he loves Hermione and wants to marry her. Then he's doomed. And he might get killed, too.
Ginny: She's destined for something big. She's the first female Weasley in generations. However, that doesn't preclude her from dying after or while doing something great. Longshot.
Fred and George: Likely one will buy it. It'll be shocking, probably the most shocking because they're close without being the main characters. F+G are serious wizards even if they are jokesters. It takes a lot of knowledge to create silliness like that, even though their parents wished that they'd put their efforts to better use. One dies, the other avenges his death and tries to live without the other (or live with a picture hanging in his room). Twins have a special bond and they probably have a magical bond that once severed, could spell doom, insanity or depression for the other. Likely target.
Percy: He's been a putz. He'll either stay a putz and pay a price for it, or he'll come back to Harry's side and have some kind of heroic death, a la Darth Vader. Likely target.
Snape: Doomed. Either he really isin the employ of Voldemort (not likely), in which case, he's a dead man for offing Dumbledore and anything else. Or he's working for Dumbledore and Voldemort will dispatch him. Voldemort suspects already. Might have something to do with an Unbreakable Vow.
Dumbledore: IF he faked his own death and is actually alive, he won't die twice. Yes, death is death but Albus seems to know a lot of the old magics, and seems to be capable of things that no one else is. Especially because he has his phoenix to protect him. Phoenixes rise from their ashes. They also have the power to teleport someone to outside of Hogwarts.
Hagrid: Hope not, but it's possible.
Neville: Better not be. He's already "lost" his parents. He's got serious avenging to do. He won't die in the process. If he does, I'll steal every copy of the book in print and edit the pages.
The other characters (at least the ones on the good side) are further to the fringe to be the ones that we are concerned about (except for the one or two obvious ones that I'm forgetting because it's nearly 11pm at night and I just got back from the end-of-term party.)
That's my $.02.
TS
Which Hogwarts student can cast any spell flawlessly?
Hermione of course. Harry and Voldemort get into a standoff and Hermione slips up and nails Voldemort.
Rowling won't kill Harry. There are 3 more movies, yet. I'm thinking that Tonks or Lupin buy it in #7.
*ouch*