Why did Itachi Uchiha set up a future for Sasuke to go to the dark side if he secretly wanted to protect him?

Chalice is right. Itachi never intended to guide Sasuke to the dark path. He just wanted his brother to become stronger to be able to defend himself and defeat Madara someday. Giving some of powers to Sasuke is another way to help Sasuke become stronger. Yet, Itachi has also considered the fact that Sasuke will be taking the dark path so as a precaution, he gave Naruto a power which is not yet revealed.