Does Sasuke stay evil

He wasn't at first, but when he found out the truth about Itachi, Sasuke became blinded by his anger and hate. He is making big mistakes that he will regret later. So yes, he is 99.5% evil( because Sasuke tried to kill Kakashi and Sakura without hesitation) and 1.5% good. That is his care for Naruto, but that is slight by itself. Besides that, he is selfish, stupid, and all he cares about is his "so called" revenge for Itachi( that is his big mistake). Naruto TRULY is the only one who can save Sasuke.