There has been lots of discussion on the consequences of Rikudo's two sons being the ancestors of the Uchiha and the Senju, but so far the Manga hasn't had any mention of his wife (of course, I'm assuming here that he needed a wife to have his two sons, and that he didn't have the power to have children himself through some special Jutsu...) I predict two possibilities: 1. This could be the last piece of the puzzle, perhaps the one thing that Madara never factored into his plans, and maybe that Naruto has inherited this other great power. 2. This is used as a last ditch effort to save Naruto at the brink of destruction, a PnJ that gives him a sudden power-up and saves the day. What are your thoughts on these and the general idea of the wife of Rikudo Sennin?