I think Naruto will not kill Sauske because Sauske was like him with few differences. Sauske and Naruto both dont have parents. However, Sauske still does have a brother, evil though. Naruto doesn't have any family. They have been rivals/friends since the begining of the series up until Sauske leaves the leaf village. Of course, Naruto is Naruto, and Naruto is unpredictable, so there is no sure answer at this moment. Even if he really wanted to in the last battle of The Broken Bond, yikes!