2 Possibilities on Madaras right eye.

[PabloEscobar]

Madara was talking about nurturing a new eye. While doubting if the new eye is going to stick with him or not so his 50-50 on this. While asking zetsu how's the battle inside. meaning black zetsu taking over obitos body. Now since he got all the tailed beast and can revive the juubi again.

First possibility is its the Juubis eye that his nurturing for his right eye socket.
Second possibility is his using black zetsu to upgrade obitos rinnegan so it can evolve to the juubis eye. The eye is what he needs for the Infinite Tsukoyomi. My prediction is he is going to have the eye in chapter 666.

 

[Deadai]

I agree
with that post.

 

[cptenn94]

I think he is probably prepareing to nuture the juubis eye.(nuture means to feed for growth to occur, so it would make sense if he feeds his eye, that it would change)

The other battle, is almost certainly black zetsubito vs kakashi and 1 arm minato. And it seems to be going well(for madara) but not over.

 

[MaGilla]

Im just gonna go out on a limb as say sasuke izanami'd madara...so we might not get to see madara's new eye if that's what he is talking about...

 

[yondaime4]

Madara could mean his rinnegan eye or he could steal sasukes or even obitos from obito and kakashim the boss has options but im not sure if taking obitos eyes would result in ems for madara or how long itd take ems to evolve to rinnegan but damn maddy is beast right now.

 

[Rikudo Ero Sennin]

I don't think it that way