More importantly I think is that they don't necessarily want dollars, but need dollars in as much as they need stuff.

Even if they kept their wealth in Bitcoin instead of Yuan to protect their purchasing power, that power is a proxy for ability to buy dollars to then exchange for stuff, and stuff is the security for debt issuance.

Debt = Dollars = Stuff

The "suddenly" part is when Bitcoin buys stuff directly, but there's a whole lot of fiat dominoes to fall between now and the final dollar dominoe.