?!?!???
No way, there's not going to be a part III, and surprised to hear something of a consensus building around that. I like Naruto too, but saying there's going to be a part III is wishful thinking. At it's core, this series has always been about Naruto's relationship with Sasuke, and there's nowhere left to explore that relationship in a part III.
This series will end, and has always been planned to end, when Naruto fights Sasuke for the last time. I'd predict the war will leave nearly everyone decimated, Madara is dead, but Kabuto is still alive and even more powerful than Madara. After an epic fight between Sasuke and Naruto ends in a stalemate, something happens (Itachi's gift? Powers of the Rinnegan? Kishimoto will decide) and Sasuke will somehow be redeemed. This frees him to fight alongside Naruto and defeat Kabuto, but not before Sasuke receives a fatal blow and dies in Naruto's arms a la Darth Vader.
After Sasuke used Karin as a shield, I think that was the turning point where it was obvious that there's no other way to end the series than him dying.