I think getting the power up of the other half of Kurama's chakra will not make him be Physically like the other tail beast. It seems that the nine tail's power on Naruto is making naruto more of the sage of six path's body. Getting the other half may make naruto become the new sage of six path. If he can make his sage mode together with complete of the nine's power, Naruto will definitely have a great fight with Madara. This depends how powerful kishi wants naruto to be.
Naruto should be already stronger than Sasuke. Naruto's power up is more of against 10 tail and madara. For Sasuke to able to fight Madara by himself should be pretty impossible since Madara is way pass the level of EMS. Even with the EMS, Sasuke might not able to beat the all five kage's together. Even so, I doubt that sasuke will have a fight to death battle with Naruto. So the power ups may not be important in the Naruto vs. Sasuke's battle. Will they even fight? The prophecy that Naruto will fight against someone with a powerful eye does not have to be Sasuke. Nagato, Obito, and Madara all have powerful eyes. Naruto fought with all of them.