Orochimaru's wording is *riddled* with ambiguity. It could mean that Tsunade is alive OR dead. Shinobi are known to talk to the deceased in a formal manner as if they were alive. Having been torn in two and forcing herself to apparently save the other Kage without the need for Katsuyas help would lead me to believe she is dying/unconscious or very likely, dead.
If she was alive, Orochimaru really doesn't have much to gain from her, I doubt she would buy into any agreement he would have to offer. However if she were dead, there are a host of possible things that Orochimaru can do. Edo summon her, infiite healing ... take her DNA for some other purpose , remember the scroll that was taken from his hideout by Suigetsu? ... I believe the "dark clouds" are unfolding to show what the real incentive is for this unlikely snake duo ... Bad times ahead.
If she was alive, Orochimaru really doesn't have much to gain from her, I doubt she would buy into any agreement he would have to offer. However if she were dead, there are a host of possible things that Orochimaru can do. Edo summon her, infiite healing ... take her DNA for some other purpose , remember the scroll that was taken from his hideout by Suigetsu? ... I believe the "dark clouds" are unfolding to show what the real incentive is for this unlikely snake duo ... Bad times ahead.