Board Thread:Boruto Discussions/@comment-37655565-20200311111242/@comment-32685487-20200311212439

Their are other Uchiha around(Shin Clones), they just aren't naturally born. They are made from stolen Uchiha DNA via Sharingan eyeballs so they are genetically Uchiha, all of them are. One of them could easily decided to try and get more involved with Sasuke and Sarada and I can see it becoming like Family to them and being accepted to having the last name Uchiha. So Sasuke would have an adopted son, and Sarada a sibling finally.