Kaguya wants a good look at Naruto and Sasuke's handsome faces before killing them.
Kaguya repels Sasuke's attack and then she opens a portal to sneak behind and grab Naruto and Sasuke. Black Zetsu appears from Kaguya's arms and starts draining chakra from Sasuke and Naruto, and at the same time Black Zetsu claims that he is the mastermind behind everything. When Kaguya's two sons sealed Kaguya away, Black Zetsu was born with the goal of reviving Kaguya, and he manipulated the Uchihas through the generations which of course includes Madara. As Black Zetsu finishes the story, Naruto and Sasuke break free from Kaguya's grip, and they realize they have to use the super sealing jutsu they got from Hagaromo to seal Kaguya away.
So Black Zetsu is true master manipulator behind all of the events in Naruto. He manipulated Madara and also Kabuto, and of course Madara manipulated Obito, Obito manipulated Nagato and so on. It's quite a long and sad history behind the whole thing. Anyways, given the final master manipulator is out in the open, this probably truly is the final battle. Naruto and Sasuke don't have much power compared to Kaguya, but their magical sealing jutsu will probably work just because. We'll see if Kakashi, Sakura and Obito will make any contributions, or maybe Minato and the other zombie Hokages will teleport in to help.