A few people think that Shisui gave one of his eyes to Danzo on purpose.
Danzo and Itachi always cared for the village, Danzo may had phucked up ways to do so but he did everything for the village. So Shisui gave both of them one eye.
I say that Sasuke could beat Danzo if he knew about Kotoamatsukami. As we the arrow´s of his Susano´o were to fast for Danzo to cast Izanagi (activate a Sharingan), he had to use the power of Hashirama. And for Kotoamatsukami he also needs to activate his Sharingan.
I think that a Susano´o arrow barrage could do the job, but I´m not sure.