Your scenario doesn't make sense. There's no reason for all these nations to be beholden to the US dollar and collapse while acting as indentured servants to the US.
It doesn't make sense. But it is a fact. The value of dollars raised by foreign corporations via bonds that have to repaid in dollars is $10 trillion since 2008.
The Hong Kong dollar is pegged to the US dollar. The Chinese Yuan has been more or less pegged the US dollar. This policy enabled China to force all savings in China into 0 profit manufacturing. Read Michael Pettis to understand the macro economics.
What you think is irrelevant. These are the facts.