I definitely think Trump would enjoy a North Korea-type situation here. A country that he owns outright where he can take literally anything he wants, rape literally anyone he wants, kill literally anyone he wants, and the rest of us have to watch him do it and applaud him during and after? What sociopath wouldn't want that? Of course, I have my doubts that he or anyone could succeed in turning us completely into that, given we have a different history as people than 1930s Germany or 1950s Korea, but there are also aspects of it that he could succeed given we also have in our history the keeping of certain castes in a permanent state of terror, degradation, supplicancy, and even genocide. Trump would definitely take a shot at making as much of that happen as he could manage to, although, at age 77, he's running out of time for that.
As for the total collapse hypothesis, the world's economy is so interdependent, with the US economy serving as its linchpin, that I don't see any way our economy could collapse and take no other economies down with it, and that includes Russia and China.