I've a strong feeling that Sakura would eventually master slug sage mode. I don't know if Tsunade has already mastered it yet, but she seems to be the only one who has made the contract with slug so far, so she might at least knew where Shikkotsu Forest is.
Also, Sasuke hasn't mastered snake sage mode yet, and Orochimaru's just come back again, so it's highly possible that Sasuke would also master snake sage mode soon.
Well, I might be an optimist, but it's obvious that Kishimoto sensei loves this Japanese legends. I don't think that he'd just let them go into dust.
And Kishimoto sensei's introduced Toka Senju (means 'peach flower'), a well-known throughout the world of her prowess genjutsu ability. Hmm...I believe that he intended to introduce her for some reasons...and one of them could be that Sakura would eventually learn her genjutsu!
BTW - Did you guys notice the hint of "the end"
this last page?
It really fits when Hiroshi Matsuyama san (the director who develops Naruto's games) (accidently) said that Naruto Ninja Storm 3 (involving the whole war arc) won't come out until Naruto series's done. Then a few weeks later, they announced that Naruto Ninja Storm 3 will come out in Spring 2013! (after that Hiroshi san seemed to keep his mouth tight during any interviews. LOL) And then, Kishimoto sensei said that he doesn't really know how long Naruto would continue, but it seems to last longer than 1.5 years.
I see people tend to look at the 1.5 years sentence, but Kishimoto sensei doesn't really know how long the story would continue exactly, so it could continue even longer than that, especially when 3 years have past, but Kakashi's year hasn't happened yet. And I think 2 years are too little to reveal things and wrap everything up IMO.
So, I believe that this war arc is the last arc of Part I and it would end around chapter 614-615, then starts with Minato's Gaiden for 5-6 chapters before we see Naruto Part 3, as early as the beginning of next year!
Well, a lot of people think that Naruto has nothing left to write, but I could imagine of many possibilities/plots, and so could Kishimoto sensei. It's a fantasy manga, almost everything is possible, and how many people would have thought that Orochimaru could come back?
However, I strongly hope that Kishimoto sensei could get his interesting story and characters development back like he did in Part I and early Part II! If he could, I wouldn't mind keep reading Naruto until it reached 20th anniversary LOL. (It's been 13 years now)
All I can do is keep hoping...=)