This is my theory. The Sage of Six Paths was the god of the Ninja world and the one who founded ninjitsu. He was the first person to defeat the Jyubi. Its is said that he had two sons, the first one had his eyes (spiritual energy), becoming the ancestor of the Uchiha (and all those with the eye justsu). The 2nd son had his body (Will of fire) becoming the ancestor of Senju. I think the key to defeating the Jyubi and restoring balance lies in possessing these two qualities. I used to think Naruto was the one especially considering the fact that Nagata an Uzumaki possessed the sharigan but apparently Madara gave it to him so for a time he had the power of the Sage of Six Paths (body n eyes). The missing key was Hinata which was revealed in 615. Hinata has the Byakugan (representing the eyes). Naruto thus its a descendant of the 2nd son and Hinata that of the 1st Son. Their powers combined form that of the Rikudo Senin. The two therefore will be instrumental in defeating the Ten Tails.

P.S. Another interesting detail is how see how Hinata's hair looks like that of the Red Hot-Blooded Habanero = #Kushina in the final page of chapter 615. This scene reminisces the battle between Minato n Kushina and the Kyubi