I've been skimming through the 5th and 6th books of the series (Harry Potter and the Order of the Phoenix, Harry Potter and the Half-Blood Prince), in preparation for reading the new book that is due out. I have my own pet theory as to how Voldemort will be killed: after having destroyed the Horcruxes, Voldemort will be destroyed and be forced to flee (or attempt to flee) into Harry's body. (I would guess that the scar will represent the last remnant of Voldemort's power.) However, Voldemort will not be able to abide the force of Harry's ability to love, and will have to let himself die. That's the only plausible theory for why Dumbledore thought Harry can defeat Voldemort with the power of his ability to love.
I also think that Snape will be the one to actually destroy Voldemort's new body: he is the only wizard powerful enough to do so. Harry doesn't have any real experience or power, and the only reason that he has defeated Voldemort several times is that he has always been underestimated by the bad guys.
Well, we'll see!