Quote Originally Posted by mage
There's no reason to hang Sai, they're ninjas. If Orochimaru wanted to kill him, the last thing hed do is hang him. I think it is possible that he's dead though since orochimaru said "No matter which way we do it, one corpse is needed now isn't it?" Perhaps Danzou wants Orochimaru to transfer him into a new body? He seems pretty useless in the condition he's in now.
This is a great theory.
Danzou wanting to learn Oro's jutsu. That would explain why Oro said that about the corpse.

Remember how Haku made it posible for Zabuza to fake a death ? Kabuto must have done something similar to Sai. And when they bring Sai's corpse to Konoha he wil revive and go meet Danzou and tell him about his mission.