Germany would be too stretched here. At the same time, I dont think a modern democracy can defeat Germany. They would simply not have the stomach for the casualties and US cant just nuke Europe all around without turning the public opinion against it.
The best case scenario I can see, is that after an economic war, limited ground offensive and a few atomic blasts, a negotiated peace is reached where Germany withdraws from all of Western Europe but keeps the East.
But a march into Berlin? No, absolutely not, only a ruthless tyrant like Stalin can.
And Japan would be a huge factor here, if Japan is defeated first, the allies might be so tired, they might settle for a white peace in Europe.
If it is a "Europe first" strategy, after gaining at a very high cost, a German withdrawal from Western Europe, which is the absolute best they are going to get. The allies say "fuck this" and settle for a negotiated peace with Japan, where they disarm themselves without occupation and keep the emperor as a divine figure.
Now you will have a still extremely powerful Germany very resentful at the west, and a beaten but not dead Imperial Japan sharing the same resenment.
After finally consolidating their Eastern gains and likely forming a strong alliance with Japan, Germany rebuilds itself and eventually become a superpower like OTL Soviet Union.
Cold War against Germany and Fascism.
The Nazi party might or might not survive, I think that the allies MIGHT be able to impose as a condition for the negotiated peace where Germany withdraws from the East, the fall of Nazism. If so, then the generals coup Hitler and stop the most vile programs like the Holocaust.
If not, then its dark, very dark times for Eastern Europe under the thumb of Nazism.
I think Nazism will, eventually fall. Germany will get fed up with the brutality, including racism and genocides.
Germany today is likely still a democratic superpower as it will not face the problems of communism. The brutality of the holocaust and the genocide of the slavic people, I hope, are repudiated, but Nazism as a whole is not discredited. Hitler is seen as a controversial figure, who while regarded as a brutal tyrant and murderer "did what he must" to bring Germany into greatness. Or maybe not and he is regarded like how Stalin is regarded today in Russia as a "great leader'.....
Likely today's Germany will try to make amendments to the slavic people, possibly automatic citizenship into Germany if they choose, like Puerto Ricans.
Oh and Japan? Well, they likely continue to be dicks and the "bad guy" of today's world.
However if Japan is still defeated, well.... since this boosts the chance of a White Peace, huge butterflies.
Germany would possible even overtake the US as the superior superpower, with the resources of all of Europe. Though today's world would likely be better, as the world would be run by 2 democratic superpowers, rather than 1 and an emerging totalitarian one.