The Idea Factory - The United States of Hate
This one would require a lot of research into history, so probably never going to write this one. The thought here is that, back before World War 2, with Jim Crow running rampant in the south, the US elects a strong man/fascist to the presidency and the party also has the house and the senate. As a consequence of that, the US joins the war earlier than it had in reality, but they sided with Germany and Italy. How that would cause a domino effect would be the big plot points of the story. What happened with the Jewish refugees, and where would they have gone? As that had an impact on the research into the atomic bomb, the US might not have gotten it. Would the Nazis still lose? What would happen in a post war US if the Nazis won? It would be different from Man in the High Castle, where the US just lost and the Nazis took over. Also, the whole alternate realities thing wouldn't come into the book.