Maybe it's Harry. Remember when Dumbledore is speaking to Harry about his parseltongue ability. He avers that Harry also received other talents and powers from Tom Riddle when he survived the death curse and received the scar.
Riddle wants to become Harry and this might be the penultimate battle!
If Harry's the Horcrux, he'll have to die... maybe Ginny's the Horcrux and he'll have to choose between saving her and saving the world...
I don't believe that but it's a fun speculation!