I'm interested in this topic because my father was a German citizen when I was born, which entitles me to German citizenship. (I've lived in the US all my life.)
Over half of German GDP stems from exports, which is a huge fraction and which is only possible because of the Eurozone and because of the Bretton Woods system. The Bretton Woods system was created by the US to help fight the Cold War by encouraging free trade and the US particularly since the election of Trump is not interested in supporting the system anymore. The Eurozone and the European Central Bank's monetary policy have been preventing the economies of the countries on the periphery of Europe from developing, and those countries will either withdraw from the Eurozone or at least force changes to monetary policy that will be detrimental to Germany's exports.
So it looks like Germany's exports will fall, maybe drastically. Taxes on the profit that German companies make on these exports is how Germany pays for its social programs.
When the economy gets bad in Germany, young Germans cannot find jobs. (France is the same way.) This youth unemployment has gotten so bad once or twice during the postwar period that people start worrying about riots and other kinds of social upheaval, which makes things bad for everyone, not just people needing to find a job. Youth unemployment never gets that bad in the US.
I don't see any challenges to the US similar to those 2 challenges facing Germany.
Although I concede that I probably would have been better off if I had moved to Germany 30 years ago in my 20s, let's see if you still think Germany is markedly better than the US in 15 years.