After Sasuke hearing the history of Konoha and the meaning on the village system, Sasuke realized that the village is a place built for peace and now wants to protect it. But is there something we still don't know about the village? In chapter 618, when it shows a flashback of Sasuke asking Orochimaru "Why did you decide to attack Konoha?" means Orochimaru obviously had a legit reason. Now I'm pretty sure Orochimaru has known for a long time the meaning of the village without having to be told by Hashirama or anybody....he was Hiruzen's disciple afterall. So even knowing the meaning of the village, he still decided to attack Konoha.
What are we missing?
My prediction, which I've been saying for months, is that Orochimaru is secretly a "good guy" who has been collaborating with Danzo all along. Some of his actions had gotten a little bit twisted, but his core mission had always been to help the village (not destroy it). Danzo famously said that he was willing to do anything to protect the village even if it meant doing bad things "in the shadows". That's what Orochimaru does: he protects the village using some very questionable methods.
The outcome of the invasion of Konoha was, arguably, good for the village overall: A new, younger, more powerful hokage was installed (something hiruzen should have done years ago). The sand village turned from an enemy into a humble ally. Many criminals and missing-nin who had joined the sound village were killed or imprisoned. Naruto, the 9-tails Jinchuuriki gained far more control over his powers.
Shortly thereafter, the disappearance of Sasuke lead to even closer ties between the sand village and the leaf village. Later, the disappearance of gaara made the alliance even stronger AND had the effect of uniting the two villages against Akatsuki (an enemy that Orochimaru, like Itachi, had joined as a spy for Konoha).
I think, when we learn the secret, we're going to see that Orochimaru was a (misguided) good guy all along.
