Madara's ability to heal fast allowed him to pluck out Kakashi's eye and use it straight away by activating the Mangekyou Sharingan ability (which is quite easy because that is the only MS move that Obito uses, and I guess Madara has seen him use it with his rennigan so he know how it works).
The only thing that can happen could be that Naruto will go to the other dimension, because he jumped out of Obito's dimension all by himself, but in the process, black zetsu will leave obito's body with the rennigan unto Madara's body. This fight is gonna become real now.
As for Naruto, I wonder what power Sasuke was asking him about cos he said you the power that the hermit gave you (he was gonna use it) but Madara switched with his shadow and went for Kakashi since he realised that he wouldn't be able to just take Sasuke's Rennigan so easy after getting stabbed!!
Now what will happen to Sakura and Obito, as well as Kakashi's eyes??? Something crazy must happen because at the end of the day, they all need to go to the real world