I believe you are overly optimistic. Had the South gained independence, it is quite possible that the United States would have fragmented further, with the Far West, the Middle Atlantic states, and the Ohio Valley states all going their own ways. Britain, France, Germany, and possibly smaller nations like Italy, the Netherlands, and Belgium would have established colonial empires in the Western Hemisphere. By 1900, the Americas, the former United States included, would have been as sliced up among the European powers as Africa of that time was. Southern independence would possibly have led to the recolonization of the Western Hemisphere and the re-forging of European chains on both Anglo and Latin Americans.
Germany would have not been defeated in WWI
A German victory or an armistice in that war would have been a better outcome for the world. Had the German, Austrian, Ottoman, and Russian Empires survived World War I, there would probably been no Nazism or fascism, no Communism, and no Muslim extremism.
No Nazism or fascism, perhaps, but Pan-Germanism was already very popular before World War I, and was indeed a component of Bismarck's foreign policy. The term and its definition were formulated in 1880, but Bismarck had already acted on it in waging the Franco-Prussian War to retrieve Alsace and Lorraine from France and eliminate French influence among the German states.
BTW, lumping Nazism and fascism together is a mistake; the Nazis and Italian fascists understood the difference very well. The best way to differentiate them is by noticing their diametrically-opposed policies toward the class system: the Italians used the class system as a buttress of the State, whose welfare they put ahead of all other considerations. The German Nazis militated against classism, which they considered divisive of popular unity: to them the German Volk and its welfare were paramount, and the Nazi state just a means to the end. The class system, by dividing the People, weakened them, and so the class system was objectively bad in Nazi theory.
Which shows, btw, that while Italian fascism and Spanish falangism were arguably right-wing, the Nazi Party was provably left-wing in its affinities to other Socialist parties of the time, shown not least by its hostility to classism.
You may be right with regard to further fragmentation.
Had the Germans won WWI the milirarism of the Kaiser would have been rewarded. You should know that the Nazi party was a product of the German Army's political manuvering and that the Lenin cell was conveyed into Russia by the German Army. Russia was a dead letter as a viable country.
Like Slavery Communism had to be allowed to expose itself through its evil deeds and impracticality.