Hey guys,
So just a quick theory - and one that's been hinted to a LOT in the series so far.
Firstly, Naruto is an Uzumaki - a clan that have natural talents in Sealing Jutsu Techniques.
In addition to this fact, throughout the series there has been a certain sealing Jutsu that has been used continuously by the main and powerful characters.
These people are
Minato: - Sealed half of the Kyuubi's Power
Hiruzen: - Sealed First, Second and Orochimaru's arms.
This Seal is of course: The Reaper Death Seal. (RDS)
The reason i believe that Naruto will use this on Sasuke is that it has been hinted all the way through.
Firstly - Naruto's father Minato used the seal on the Kyuubi to seal inside Naruto, it was the ultimate sacrifice to save the village.
Next, Hiruzen protects the village from Oro and his edo's by using the very same Jutsu.
Sasuke is a major threat to the leaf and the ninja world as a whole, but Naruto could never just kill him outright - and it is unlikely that Sasuke will just have a change of heart. The RDS is a legacy passed down through the village for its ultimate protection.
The final hint that we've been given was in Naruto and Sasuke's last meeting where Naruto says 'We will die together" hinting to them having the same fate in the end. This would ultimately end the endless cycle of revenge - a hero ending it by sacrificing his life for the greater good - during an international war.
As for learning the RDS - The Kyuubi has seen the technique before - it was how he was sealed - furthermore, Minato may have left hints on how to use within Naruto on the seal itself.
Of course, i would love to see Sasuke have a change of heart and come back to the village. I would also love to see Naruto as Hokage - that's the whole point of the story and it's most likely what will happen. Perhaps Kurama will sacrifice his life in exchange for saving the rest of the world?
What do you think?

:sasuke: :naruto: