Yeah but he also wants the renewal of the uchiha clan... So maybe for that he might want to kill madara... To get the nickname of the best uchiha like madara has...
Even so... I'm almost certain... Itachi left something to sasuke before he disappeared with the eso tensei.... And maybe he will awaken the rinnengan... And naruto still has that "knowledge" that the bijus gave him and we still don't know what it is... And the juubi will awaken... And possibly sasuke will be its jinchuriki.... So u can't say that they can't beat madara... It's possible.
Maybe because of it being the only type of way for Sasuke to redeem himself since the whole main point between Naruto and Sasuke is Naruto trying to save Sasuke.
But well if you want then you could have Naruto vs Sasuke and Naruto killing Sasuke and saving the world, and there you have it Sasuke never worked with Naruto.