Well, Mitteleuropa would probably require significant investment into defense and security. After all, why would Eastern Europe and the Balkans suddenly change their minds and become open to German rule? More money spent for the military means less for welfare and, well, everything else. Plus, I'm not so sure that no Nazis = no brain drain. You could still have an authoritarian regime without the death camps, and antisemitism has a long history in Europe.
Give me a Soviet Union and yes, the Germans are going into high defense spending mode, akin to the USA post-WW2, even a revanche despotic Russia might drive up security concerns, but that also pushes all East Europe to see Germany as its better protector, perhaps just as uneasy as Europe felt subordinate to the USA through the Cold War, but I do not see East Europe being treated as the Warsaw Pact got treated by the USSR long term. Germany is getting back to its evolving democracy, it is heavily influenced by both Liberal and Socialist thinkers, the SDP likely comes to assert dominance but Zentrum will be a political powerhouse for years to come, the Catholic political stream likely shifts centre-right as SDP consolidates the left, leaving the Liberals as coalition swing voters, and how are these political parties imposing oppression writ large? This is Weimar painting inside the lines under the steady cap of a monarchy, more like Britain really, just that its left is more openly socialist and its right more influenced by Liberals with a dollup of Catholic political theory running down its middle.
Germany will be even more the economic center of Europe and without the disorder on the right, ultra right political revolutionaries likely cannot gain momentum, pre-war the most vocal anti-semetic party lost seats and faded, with a monarchy in place you anchor the conservatives away from Brown revolutionaries. The far-left is starved by SDP and cannot foment revolution, further draining the far right of meaning. Assuming Fascism is invented, it has more fertile soil in A-H than Germany, but yes anti-Semitism will remain a back ground form of racism, yet Germany has more groundwork to become the least anti-semetic country, its Jewish populace are rather nationalistic and generally not religious, culturally I see them assimilating at least as deeply as American Jews have, suffering a sort of snobbish discrimination that fades and has no effect as Germany becomes more secular.
Germany likely sees net migration and more diversity, not to the level of the USA, but then the USA has white washed its diversity into a very WASP façade, but you have Italian, Austrian/Russian Poles, and more seeking work and opportunity in the biggest economy, Berlin will look like London, cosmopolitan, the grumble will be all these other Europeans just want our Marks. But has that fuelled ultra-violence in the UK or USA or France? Immigrants bring challenges but Germany should be no worse off in assimilating them than other European cultured states have.
You might see odd things like a bigger Chinese population if German ties into China deepen, so Berlin gets a vibrant Chinatown, or more black African immigrants should her colonies be regained. We may see less Turkish Muslim immigration as the OE might do better, or you may see an Arab influx instead. Germany developed huge trade with Latin America, one might see an odd patchwork of South Americans doing business in Germany, and we might see German culture survive more openly in the USA, linking Germany to the USA in ways similar to and competing with the British connection. France may stay out or seek union with the German led economic order, pre-war the Socialists were seeking rapprochement, that may return, or even more strangely the French right might realign with this Monarchial Germany to back stop the further shift left in French culture, politics and power. Post-Versailles is a mixed bag of lampposts that illuminate only parts of the path and leave a lot unknown.
This post-war has a longer survived British Empire and potentially longer lived racist imprint in the USA, these two may not look so bright or shining in example, Britain fighting wars to back stop independence, the USA lazily overlooking its own discrimination. We might see more Franco-style regimes in Southern Europe, Mussolini being an example of how to get things done, while the USSR carries its gloss of prosperity too, fuelling disorder globally. It is easy to think the USA will be number one and the Germans are just well-dressed villains, but I think those tropes are butterfly food.