Even though he uses Kamui, he won't be able to escape Madara's chakra rod controlling. That's the biggest disadvantage over his advantage, unfortunately
Are people really forgetting that if he uses Kamui to teleport a body part and such, Kakashi will kill him? Don't forget that Kakashi is in the Kamui world.
The extraction is complete so he should be on his death bed. But he should be able to stay alive because of the zetsu body (at least dor a little while). I think he will entrust his eyes to someone- oro or kakashi. While he is doing so, madara swoops in and destroys them so they can't be used against him or something