Has anyone considered that while Hitler coming to power in Germany is unlikely, it is possible he could become Fuhrer of a revanchist Austro-Hungary. Consider this scenario;
i) The Austro-Hungarian Empire was very corrupt, very incompetent and very inefficent pre-World War I and a victory in the conflict would make the problem worse because of complacency (think France in the 1920s/30s.
ii) This causes the middle classes and many of the ethnic groups began to hate the Dual Monarchy even more. Instability grows, especially after the empire actually grew after the end of the war (annexation of parts of Poland and maybe Serbia).
iii) Then Hitler turns up, turning their rage against the Jews, Italians, north Germans (Prussians, Hannoverians, Saxons etc...), who are betraying the Austro-Hungarian empire. The Slavs (with the exception of the Czechs and Slovaks), might also be a target for Hitler's rants in this TL.
iv) How Hitler could come to power is open to interpretation; the Emperor might be forced to appoint him chancellor if and when the Nazis gain a significant portion of parliment or alternatively, there might be a revolution (March on Vienna?) which topples the Imperial government.
v) How would World War II pan out in this TL? A Nazi Austro-Hungary would probably ally with France (which would almost certainly undergo a shift to left or right and becoming revanchist, France in OTL became defeatist because of how quickly Germany recovered, not because of the actual fighting in the war) against Germany. They might also be joined by Britain. In that case, the situation for the Germans would look very bleak and they would probably only be saved by a Russian intervention, which I suspect would be unlikely (Russia would either be too weak or use the opportunity to gain territory at Germany's satellites expense).
Here is what I think a probable WW2 in this TL:
AH/France/Britain/Spain vs Germany/Italy/Bulgaria/Romania
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I understand that this is probably completely ASB, but it's fun to speculate.