A rather unlikely map I made a while ago of Austria taking the place of Germany in the Second World War.
I did make a basic timeline and indeed a series of maps for this, the basic idea is thus:
Franz Ferdinand is not assassinated, and implements the United States of Greater Austria plan. The Hungarians however are not happy and formally walk out, taking half the empire with them. The Austrians are annoyed at the Germans for not supporting their threats towards the Hungarians and even blocking them declaring war, so they cancel their alliance and move more towards France and the UK. Germany on the other hand signs alliances with Italy, Hungary and Russia.
WW1 still comes along; Germany, Russia, Hungary Serbia and the Ottomans vs. France, Austria, the UK, Italy, Romania and Japan.
There is severe fighting in Austria, as German forces invade from the West, Russian from the North, Hungarian from the East and Serbian from the South. However France and the UK manage to hold German advances in the West and capture German colonies, Japan and the UK take Russian territories in the Far East and the Ottomans also suffer. By the end of the war the Central Powers are defeated, although much of Austria is devastated. Following strong Austrian demands Germany is split up into 5 separate nations (Prussia, Hanover, Saxony, the Rhineland and Bavaria) and Russia (who underwent a Communist Revolution so were willing to sign a Brest-Litovsk-like treaty) also looses Finland, the Baltics, Belarus and Ukraine, along with territories in the East. Romania gains Hungarian and Russian lands, whilst France reclaims A-L and Poland is given independence from German and Russian lands.
Over the next few decades the NSÖAP (Nationalsozialistische Österreicher Arbeiterpartei) rises to prominence in Austria, calling for unification of the German lands under Austria along with claims on Hungary, Poland and Serbia. They claim that Austria gained no territories from the Great War in which it was devastated, which is partially right (The Western allies were happy to split up Germany, but didn't want to give Austria back Hungary given that they partially sympathised with the Hungarians demand for independence, similar to Poland.)
In 1933 Adolph Hitler is elected Minister-President for the NSÖAP (commonly known as the Nasop - Naz-opp Party), a slightly less radical version of OTL Hitler given he grew up in a more tolerant USGA Austria but still intent on rebuilding the borders of a new Vienna-centred Holy Roman Empire.
In the 1935 Budapest Agreement Hungary is reunited with the rest of the Austrian Empire.
In 1937 the Munich Anschluss is enacted, annexing the nations of Bavaria, Saxony and Prussia to the Greater Austrian Empire.
In 1939 Emperor Franz Ferdinand is successfully assassinated by Yugoslav rebels when visiting the city of Sarajevo, 25 years after he survived a similar attempt in the same city. Hitler declares himself temporary (Yeah right) leader of the Empire and declares war on Yugoslavia. Due to their alliance Poland and Russia also join the fight, which drags in France in 1940 once Austrian troops invade the Rhineland.
This map shows the Greater Austrian Reich at its maximum extent after the Treaty of Versailles ends the war with an Austrian victory. Greater Austria annexes the Rhineland, Poland and Yugoslavia, whilst France is split in two to complete Austrian domination of the Mediterranean.
Hitler in this timeline is if anything much more sensible from OTL, he refrains from attacking any of the Behanelux (Belgium, Hanover, the Netherlands and Luxembourg - TTL version of the Benelux) nations so as to keep Britain from entering the war, likewise the eastern states serve as a fine buffer from Soviet Russian aggression.
The Reich is unstable, although better than Nazi German due to the USGA plan giving many more rights to minorities. Sure it's a dictatorship, but not a mass-murdering one like Nazi Germany. However weather it can hold onto the power it has over Central Europe remains to be seen...