Spoken from a European perspective: within a few decades, the US will lose its status as a superpower as it slides into isolationism. You simply cannot be both isolationist and a military and economic superpower. Add to it that much tech is still in the US, but people are waking up to the inherent vulnerability in that. Think government data being on US servers.
These developments will hurt the entire world in the short term and new superpowers will rise. Russia has had its day, but China and India will be the top dogs. I am not discounting Brazil either as a local superpower is South-America. We do probably not want it, but they have the people and the production capacity.
The next four years will accelerate all that. I have already read the first questions about F-35 warplanes being a wise choice as the US could potentially disable them remotely. That would turn them into expensive paperweights at the whim of the US. If the US themselves are less than stable, that would be a very precarious situation.
One reason I have not read yet: scapegoating. In my country, back in the early 2000s it was the “terrorists” who made it possible to enforce a few unpopular and unconstitutional policies. Nowadays, it is the “immigrants” who take our jobs (we have a job shortage), housing (which was sold off to investors) and health care (which was sold off to investors). Point to a group that cannot defend itself and people will vote in your favor.