Kishi didn't say it that way.
He said something that everything will be revealed/resolved, around the Juubi, Madara and Sasuke. He didn't say Naruto will fight this, then that and that one.
Besides, if you want to introduce a new villain, you won't give it away like that anyway, like saying "Naruto will deal with Juubi, Madara, oh, and then I bring some new female villain named Kaguya, surprise!, and then Sasuke!"
He said something that everything will be revealed/resolved, around the Juubi, Madara and Sasuke. He didn't say Naruto will fight this, then that and that one.
Besides, if you want to introduce a new villain, you won't give it away like that anyway, like saying "Naruto will deal with Juubi, Madara, oh, and then I bring some new female villain named Kaguya, surprise!, and then Sasuke!"