The success of the manga relies on Orochimaru, and Kishi know it. After the war, the villain will be either Oro in Sasuke's body, or Sasuke fused intentionally with the white snake. This will be the last twist to prove that all Itachi's life was a failure. The reason I am certain of this is that I think the snake land and the white snake form a power that used to rival with the SO6P while the toads were allies of SO6P. After the Uchiha vs Senju finale, it will be SO6P vs his rival. This mean a fight between Rikudo Naruto and a fake Rikudo Sasuke.
Believe me or not, everyone will turn Rikudo (super sayan) at the end.