Plot.

"So I don't care if I'm going to be ripped to shreds, I'm still going to take Sasuke back from Orochimaru!!" -Naruto (ch. 303)

...One year later...

Ironic.

Good effort brings great fortune, as they say. Naruto gave all of his effort (maybe even more) into the mission of saving Sasuke. However, all of that effort went to waste. When Naruto, Sakura, Sai, and Yamato went back to the Otogakure with a new plan to save Sasuke, they depressingly found out that Orochimaru was now the occupant of Sasuke's body. Sasuke was gone; completely gone.

This was quite devastating for both Naruto and Sakura...
To anyone who cared, it was shocking, if not devastating.

Shikamaru, Ino, Chouji...
Neji, TenTen, Lee...
Shino, Kiba, Hinata...
Gaara...

Everyone who believed in Naruto felt bad for him.
But, you know, when your friends fall into depression, you can't help but feel bad for someone you love, be it kinship, friendship, or crush/love. They didn't lose hope, even if Naruto did. Naruto watched their backs, now they have to watch his.

And now,
Orochimaru plans to use Sasuke's body and get rid of Itachi. Itachi is a problem, so it the rest of the Akatsuki. But since Sasuke's power, chakra, and Sharingan are with Orochimaru, Orochimaru has the upper hand.

Konoha isn't under attack now since Orochimaru's plans are to exterminate Akatsuki. Konoha also has the same plans... But the two nations aren't allied. Can they be allied if they are in that much need? Also, since Orochimaru has possession over Sasuke's "evil chakra" that Uchiha, Madara had, can Naruto and the rest of Konoha stop Orochimaru?