It wasn't much of a surprise. Orochimaru still has his interests in Sasuke. He's waiting for Sasuke to reach his decision and take his body. But he seems more fatherly/sensei-ish toward Sasuke now. A lot like Jiriya and Naruto and Tsunade and Sakura.
I had a feeling tsunade would live along with the five kages, orochinaru turning good, but kakashis death.. so unexpected. Why would kishi take a character that's been with us from the beginning T.T