Orochimaru said he doesn't really care for this war. It is currently unknown if he is going to help in this war. If he and Sasuke don't help, and the war ends, there could be a potential arc after the war. But why wouldn't Orochimaru want to partake in this war? He has so many opportunities here:
1. Sharingan - He has wanted Sasuke's body for a while now, because he wants to unlock the full potential of the sharingan and many other jutsu. In my opinion, I don't think Orochimaru would be able to take Sasuke anymore. It is still currently unknown how strong Sasuke has become, since he hasn't actually used his EMS yet.
2. Rinnegan - It is unknown how much Orochimaru knew about the rinnegan. The fact that he wanted Sharingan and fooled around with Hashirama's DNA gives reason to believe that he knew how to unlock rinnegan.
Let's say that the Allied Shinobi weaken Obito... or Madara comes back to life (not edo), and they weaken him severely. Orochimaru would have a perfect opportunity to steal some bodies, both Madara and Obito being Uchiha. He has access to Obito's Rinnegan and Mangekyo, which has Kamui. He would also have access to Madara (granted he comes back to life and is severely weakened), which gives Orochimaru access to EMS and Rinnegan combo.
3. Juubi - In addition to the above, Orochimaru would have the golden opportunity to become the Juubi host. Orochimaru has always wanted power. He has always wanted to master ever jutsu. And he has always wanted to become the greatest, most feared shinobi around.
If he lets the Allied Shinobi do most of the work, he has the opportunity to get most of these things and become a major antagonist again.
So... why wouldn't he want to partake in this war? Why would he even help Sasuke, besides the fact that he wants his body? Do you think he has cooked up a plan already?