Rowling has said that characters will die. There's at least one death coming up in the seventh book, and probably a higher body count in the last two. Here are some guesses at who's going to live to the end of the story and who isn't...
. Harry dies, but comes back! Look at all the phoenix imagery we've gotten-- the feather in his wand, the help he's gotten from Fawkes, not to mention the Order of the Phoenix in book 5-- and keep in mind the parallels between him and Voldemort, who has come back to life after a fashion.

. Hermione lives but gets to have a massive emotional crisis.

. Ron lives and comes through the whole experience relatively undamaged.

. Neville lives although I predict some close moments when his powers really start to show themselves.

. Cho Chang lives if she doesn't get involved with Harry again and stays out of Ginny's way. (Involved with Harry? Since Harry's first attempt to ask her out didn't go well, and they were together a second time, they are plainly destined for each other. :-) Being the hero's girlfriend is a perilous occupation, but if she can avoid having a moment of true romance with him before, say, the second half of book 7, she should survive okay.

• Snape is half vampire.
• Draco is part veela and tries to use his chamrs to seduce Ginny to find out what he can about Harry.