I wholeheartedly agree that confidence in the value of any asset, commodity or currency is of fundamental importance.
Fiat money has value only as long as we maintain confidence. So I agree that it is possible that there could be a sudden exit from the the $US, which would have severe consequences. I am a bit reluctant to predict the end of the world because I have witnessed the relentless rise of the housing market which seems to have no limit. There are good reasons to explain why the housing market has yet to collapse, but if the US suffers more trauma such as what might happen if the coronavirus runs out of control amongst 60% of the population (currently 0.25%?) then I agree that we in Australia would also suffer.
