C'mon..Kabuto have lived and breathed to be Orochimarus little pet, Its perfetc that he is the next supervillain in the story, when the Akatsuki act is over..
...It would be a more of a waste to let Sasuke "transform" into Oro. He has evolved alot through out the story, and technically he isn't a "bad guy" so it wouldn't make sence if he just dies and let Oro take over.
But Im looking forward to see that old pedo face again, Its a shame that he died so quickly aganist Sasuske, but he was sick so it can't be helped..
But its 100% that he is gonna jump back into the story, otherwise we wouldn't have seen him fight naruto and Hineta etc back then, giving info..