Board Thread:Naruto Discussions/@comment-25178929-20140919183238/@comment-24593592-20140925012810

There really is no indication that Sasuke has returned. The only way that can happen is in a prison cell.

People in their 50s can have children and Tsunade body is that of someone in their 20s-30s. It is also never stated that she was the last of the Senju.