Sasuke's Kusanagi isn't the same legendary Kusanagi sword of myths that Orochimaru had. Yes, long live the Uchiha clan when its only 1 member left after all this is done. Itachi had it bottled up in him this information for like for ages before Sasuke was able to come for him, of course he would show emotional stress. If i was the mangaka i would kill Sasuke off with Itachi just for the sake of it. That should evolve Naruto's character even more than just the death of the toad sannin, but sadly i'm not and i am pretty sure Itachi is the only one that will die seeing as Sasuke is Kishimoto's fravourite character
"This is a world where people's hearts are filled with hatred. Where fingers have no purposes other than to pull triggers!"