Naruto saw the hesitation in Sasuke. In the original story, Sasuke had never proactively involved himself in anything outside of vengeance; his entire being was consumed by the fires of revenge, unable to extricate himself.
However, having been influenced by the time-travelling Naruto and the time-travelling Sakura, he had also begun to occasionally ponder matters beyond vengeance—such as how to revive the Uchiha clan after taking revenge, and whether he should continue staying in Konoha as before if he were to revive the clan.
Lost in these thoughts, he heard Naruto saying, "I know..."
Chapter 73