I'm not much of a fan of alternate reality. On the one hand even the tiniest permutations can cause differences that would make the world unrecognizable. This is the "Butterfly Effect". The objections that Jack Campin raises are valid, but only a drop in the bucket when it comes to how the major changes listed in the opening post would have altered our current world. On the other hand there is a cause and effect element in history. With the numerical and manufacturing superiority of the North rhe Civil War could not have ended any different than it did. Chance can come into play but only so much. Some might believe, for instance, that had Lincoln been killed 3 or 4 years earlier it might have changed the outcome of the war. It would not have. Even if another world power had come in on the Confederate side, the war may have been prolonged, but the end result would have been the same. Individuals can impact history but here again only so much. Other forces like group dynamics and the momentum of systems have a bigger influence. That's one of the major themes of Tolstoy's "War and Peace".
   I like good historic fiction, where an author injects interesting fictional characters into history, but it's important that he not fundamentally change that history. That's the one thing I disliked about the recent movie "Inglourious Basterds".