Even though it's not officially confirmed there's hints the new villain is Shisui Uchiha. One of the biggest hints that I don't see discussed is that Kabuto didn't find his corpse. In the manga Danzo stole his right eye and because of that I'm sure he hates Danzo because of it. He probably knew about his sharingan arm and found a way to do that himself (even learn how to put it on his head) he probably thought he could get revenge on Danzo if he did the same thing (be on the same power level). He probably resents Sasuke because he killed Danzo, but also killed his best friend Itachi. When he saw Danzo died, he took the opportunity to take his eye back. Because he saw his eye was severely damaged he tried he best to restore it, this is probably why he has those stitching on his eyes. I also think the new sharingan pattern is the ems version of his original mangekyo.
Shin is probably a victim of Shisui's KA and is using him as a puppet. I think Shisui might use KA on either Naruto or Sasuke, but most likely is Sarada since that who he's after. If Sarada gets caught with KA, Sasuke could undo it with his rinnegan. He might even save Shin this way if my theory ends up being true.
Shin is probably a victim of Shisui's KA and is using him as a puppet. I think Shisui might use KA on either Naruto or Sasuke, but most likely is Sarada since that who he's after. If Sarada gets caught with KA, Sasuke could undo it with his rinnegan. He might even save Shin this way if my theory ends up being true.