Just read an interesting theory on a blog. Quote:
In Harry Potter and the Deathly Hallows, Harry will face an existential crisis—the only way for him to kill Voldemort will be to do immense damage to himself, and possibly die in the process. In the face of immense temptation to switch sides, he will choose to kill Voldemort, and will lose all his magical powers as he does so. In other words, he will become a Muggle again.
I think it might happen. If harry lives though I'm sure Hagrid/Ron/Hermione/Lupin will die.