Even if sanity and democracy are brought back by a future adminstration, the US public have proven they can't be trusted not to vote in another clone of their current dictator. DJT Jnr and Barron will probably have a shot at the title in the not too distant future to maintain some kind of North Korean-like dynasty.
There's enough of an undercurrent of overconfident, no-consequence, chest thumping "individuality and independence" in the US that, unless complete ruination occurs this time around, they'll vote for having another bash at complete ruination.
Good trade relations is what keeps the trust and respect for the laws of the US in place in other developed countries. Copyright for example. If the US isn't a reliable trade partner then their power to influence copyright laws around the world would rapidly diminish, which Disney wouldn't be happy with. (I'm sure there are other examples of this, but international US copyright Law is one I'm vaguely familiar with. Use of the US Dollar for trade is another possible avenue for decline of US global influence).
Yes, the US could be self sufficient to keep it's entire population alive and well, but not with the lifestyles to which many of them have become accustomed.
They also need to fix their voting rules and gerrymandering.
I hope.
... and something like half of the companies comprising the US GDP.
Much of the value that the US exports heavily depends on foreign nations enforcing intellectual property rights for the US.
If the world decided that the US is hostile and stopped enforcing US trademarks, patents, copyright, and trade secrets... it would be over for the US economy.
Any software could be "stolen" legally by anyone and sold under the original name and the US could do nothing about this except stomp their feet and threaten military invasion.
China and Russia already do this to an extent, but if everyone else did it too, it would be curtains for: The entire US game industry, movie industry, music industry, software industry, and more. Pharma and manufacturing would take a hit too.