Madara will have three eyes!

[Kishi Uzumaki]

This is plausible .

i thought it's byakugan or eyes first because of the left dots corner ( there's a black line ) , now i think , it's the way you explained .

i think , Madara was talking about his right rinnegan but it can be what you say too .

maybe that eye will be replaced in Madara's left eye socket ( he don't have a eye there Lol )

 

[Behemoth55]

I think, Madara will get his other Rinnegan and that's it. After he's defeated, Kaguya will brake out of his body(probably). However, you could be right too. Madara releases his chakra at the end of chapter 673 though. There is a meaning behind that. But I would like to see how Sasuke would show us the potential of Jūbis eye not Madara.

 

[iNotorious]

Maybe maybe Everztar!

Liking these theories :3 <3