I recall once being in an argument with someone about the possibility of Kabuto being THE major villain in the end, because, after all (in their view), what is he but a lesser form of Orochimaru?
Well, in this chapter, he's revealed as someone who surpassed Orochimaru in pretty much every area Orochimaru had specialized in, and has incorporated all of the powers of Team Taka... except for Sasuke... (so far).
As I said a few chapters ago, I don't think things are going to go according to Itachi's plans in this battle....
Yeah, I think I remember Kungfu Truffle saying that a while back: Kabuto could easily be the major villain because he had detailed notes on all parties, focusing on strengths/weaknesses; had medic-nin abilities to heal on par with Tsunade/Sakura; and had an unknown motive. He's a super-villain in the making.
My first thought on this chapter was that by Kabuto going to great pains to explain each of Team Taka/Hebi's skills, he was setting up events to come.
From here, Sasuke either has to turn to good (by Itachi's influence) or turn really, really bad. Well, if Kabuto has these powers morphed into him, and one of the snakes bites Sasuke, then isn't it possible that Sasuke could then be "infected" by all those powers. Making him supremely evil and powerful? And potentially Kabuto's puppet....
It could be that Kabuto's ultimate goal was capturing Sasuke, whereas Madara's goal was capturing Naruto. And if Sasuke's sharingan can control Naruto, then this would be the ultimate power struggle in the end. Those two men for ultimate control, and the the two boys fighting to regain self-control and possibly to help each other.
The only thing about the Karin background is that it makes me wonder again about Sakura's. Could the pink hair mean she's a descendant of both Uzumaki and Senju, making her an ultimate healer? Anyway, the more other minor characters are fleshed out, the more it is glaringly apparent that Kishimoto is withholding Sakura's background info.
Lastly, desaix I've been up in your neck of the woods the last week or so: Just got back from seeing the cherry blossoms in DC and spent a few nights in Ashburn!

It was lovely!