The American Empire never existed, because it never could. The US made the explicit decision not to occupy the defeated forces after WWII, save for strategic forces in place to protect the interests of the host countries. The US opened its market (the only market of size left and still the largest consumer bases in the world, by far) with no tariffs.
What the US got in return was cheap goods and a whole lot of debt. What the world got was stability. The US is no longer interested in subsidizing the global order.
The current discussion re: “bringing back manufacturing” is making the mistake that everyone always makes when Trump is involved: taking him at his word. The point isn’t to bring back all manufacturing. The point is to profit off of imports. Some manufacturing will return — whatever is high value added and benefits primary from cheap shipping internally - but nobody thinks that Americans are going to sew t-shirts.
Also, those who are looking for an American decline as comeuppance for being unkind to allies are going to be sorely disappointed. The US has everything it needs to be self sufficient, and no matter how batshit crazy the leadership is, it’s still — still — the safest place to park capital, still the largest consumer market by far (more than twice China), has a stable demographic and a middle class country to its south that brings in lower cost workers as needed. Not to mention being totally energy independent, bordered on two sides by oceans and with more potential port coastline than the rest of the world combined… and also holding the virtually all of the world's supply of high-purity quartz, which is a requirement for semiconductor production.