Do you remember when Naruto Joined the battle field and Dan thought he was Nawaki? Do you think the same thing will happen when/if Sasuke joins the war and Madara will at first think he is Izuna. Izuna was designed to look like Sasuke.
you're not curious as how Hashirama,Tobirama or Hiruzen would confront Madara.Sasuke and izuna have a striking resemblance in their hair styles....i want to see how sasuke confronts madara and minato confronts obito......