As we saw in the movies, Sasuke decided to train Boruto.
Spoiler :
In order to do that she would need to become crazy powerful. She is also Sasuke's only child, and top of everything a child who inherited Uchiha's KKG. There is really no better man to train her than the man who mastered Sharingan. Maybe Kakashi, but he is too old. It should also be considered that Sasuke's wish is to restore powerful Uchiha clan.
So why do you think he chose Boruto over Sarada? Maybe she didn't want Sasuke's help? Is it possble that Sasuke somehow knows what threat will come to Konoha and decided to train up Boruto in order to stop it in the future?
Share your thoughts. :3