Board Thread:Naruto Discussions/@comment-24824148-20140530171031/@comment-1512913-20140531113930

I think he realized that Sasuke is much stronger than himself, there's no way he will get his body, so instead of attempting something infeasible, he has allowed Sasuke's personal growth instead.

Basically, he took a backseat, having decided that witnessing Sasuke's power (rather than having it) is better than nothing.

Or perhaps he knows Sasuke's true intentions as well and whatever they are, they may be beneficial to Orochimaru's own agenda. We will see.