Just my theory. But Sasuke will be the only one to seal Madara. He's going to use the Totsuka blade. Remember when he and Itachi first fought and Itachi touched Saskue's head with his finger. He gave Sasuke a new power (MS) with that one touch. Well remember what happened after Itachi and Sasuke defeated Kabuto? Itachi touched him again, but this time they touched foreheads. I'll bet my left hand (my dominant one) that Itachi gave Sasuke another power. Most likely the Totsuka blade for his susanoo. Which is a sealing blade and probably the only thing left that can actually seal Madara without fail