Sorry for reposting, but here i mention when we might see him!
Remember the sage of the six paths wanted to change the world?
but he couldnt, because his time had come, and he was dying! - so do u think dying could actually stop the great SO6P?! -the greatest ninja in history! - ofcourse not!
do u think he could not be immortal if he wanted? - orochimaro could!
so why didnt he?
i believe its because later on he knew that generations would have to pass before he would have a another chance! - so before he died, jubis chakra was not the only one he divided!
i think he hid a big part of his own chakra inside the kyuubi!, already knowing about the prophecy of naruto! - thats why after naruto was able to partly control kyuubi - he started looking like SO6P! - because he also gained part of SO6P's chakra!
"afterall, the frog sage could see the future, so why not the greatest sage of all, SO6P?"
so in the end fight - naruto will have full kyuubi, and SO6P's chakra! - and i strongly believe that, thats when we actually see the real sage of six paths inside narutos mind, giving him advice and alittle help to win against madara, like kushina and minato!
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a possibility..
since we havnt seen any main characters die in this war, it is possible that madara will kill many of them!, even sakura or hinata just to show his power!
kushina with her last chakra helped naruto control kyuubi, minato with his last chakra helped naruto suppress the kyuubi!, and SO6P Will use nagatos jutsu to bring back the main characters in the end!
but ofcourse naruto will get the credit in the village!