Anyway, since we have confirmation that players can be horcruxes, my thoughts, in order of probability is:
Harry Potter is a horcrux
Voldemort is considered a horcrux for the purposes of victory.
If Voldemort is not killed after all horcruxes are destroyed, another scum member becomes Voldemort.
All but one horcrux was destroyed at Hogwarts, so I think it's plauslble that there is exactly one horcrux in the locations we cannot access yet.