Is he going to try to get Sasuke's body again? or something new?
Orochimaru isn't back, his soul have been seal (this just a small part of him). I think he probably would try take over Kabuto before Sasuke, since he probably won't be able to move
I hope he's back temporarily because we've had enough of Orochimaru, he has been the longest villain on the show so he doesn't need anymore scene time.... Itachi sealed him completely so the remaining parts of him must remain in Kabuto but now that Kabuto has mastered Sage Mode how will Sasuke possibly find a way to reach Oro? Oro at the moment doesn't stand a single chance against Tobi or Madara so he won't pose a threat unless he pulls something special up his sleeve. I'm guessing that Sasuke is going to contact Oro by using Kabuto as a phone sort of with his sharingan.
...Orochimaru, he has been the bestest villain on the show so he needs more scene time....
I wouldn't count him out against Tobi. Tobi's feats are getting beat by the 4th Hokage in seconds and having his invasion plans fail completely, failing to capture the Jinchuriki, having his personal hand-selected goon squad quit on him or get beaten to a pulp (often by children), and getting blown in half by the weakest Akatsuki member, despite his intangibility. The only success he's had is sharinganning the former Mizukage, who may have been a child at the time.
Orochimaru stacks up well against that.