There's a lot of folks who've theorized that a piece of Voldemort's soul is residing in Harry, Voldemort having inadvertantly created a horcrux in Harry when he murdered Harry's parents. And there's a lot to be said for that theory, I think.
Of course, unless the horcrux is destroyed, Voldemort can't be killed. So Harry Potter must die in book 7 if Voldemort is to be killed.
But no one said that Harry Potter had to stay dead.
Clinical death might well be enough to banish the bit of Voldemort's soul from Harry. And there are a number of candidates for the job of reviving Harry. Hermione, Ron, Snape...