To be pedantic, that's not "historical fiction", that's "alternate history fiction". Historical fiction is like the books by Ken Follett, about medieval Europe

To be pedantic, that's not "historical fiction", that's "alternate history fiction". Historical fiction is like the books by Ken Follett, about medieval Europe. They're set in that time, as we understand it historically, but the characters and events are fictional. What you're describing is alternate history: it's fictional work that assumes something went very differently at some point in the past, and then attempts to extrapolate from there how history turned out. For instance, suppose the US had never gotten involved in WWI; how would the later 20th century have turned out? Or suppose Al Gore had won in 2000; how would things be different now?