How deos Sasuke know he's truly changed? Cause he joined the other villages which was to fight against people who were a threat to himself aswell as the whole world? If the Cloud wasn't going to be affected by IT then i doubt he would have ever cooperated with them,infact he probably would have acted like he did while really planning on their demise like he did in the Hyuga incident.
Who knows that the Kages will really stay united after this war which they only fought together in cause they were all danger.The Tsuchikage and Raikage have always been shady.Think about it,why would the world not follow Sasuke,the person who saved them from IT and the Akatsuki.How would they even know he killed the Kages unless Naruto,Kakashi,and Sakura are alive and tell and or Sasuke tells them? It's like what Alpha said which didn't even think of.
What Tobi told Sasuke about the Uchiha and Itachi was true,which Sasuke confirmed when talking to Danzo at the end of chapter 476.The only thing Tobi lied about was the Kyuubi attack,he said it was just a natural disater.Sasuke deciding to kill the Elders wasn't insane,but wanting to destroy the whole Village was wrong,but understandable to why he wanted to do that.Deciding to protect Konoha after talking to Hashirama wasn't insane,nor is deciding to change the messed up Shinobi world and System,then create a new better one.
Nor is killing the Leaders to the messed up Shinobi world and system.The Shinobi Nations got into 3 Big wars and killed many people,Shinobi and Civilans,do you call them insane? The Akatsuki wanted to force change in the world,do you call them insane? Nagato actually destroyed Konoha,do you call him insane? Have you and others who complain about Sasuke even thought of that?
I'll go into more detail in my own thread later.