The funny thing is. China can talk about removing the U.S. dollar and trade when Yen. But they need a stable currency to convert between and so conversion is still done with the U.S. dollar. The U.S. dollar won’t be removed from trade in our life time.
China doesn’t let the RMB float freely, so trade still happens in dollars. Also, the American government buys a lot of treasuries, so it’s easy to save a few billion quickly when you need to, which isn’t really supported by any other currency…saving money by lending it to the USG conversely prevents it from re-entering your own economy and stoking inflation (China isn’t the only country to use the USA like that, Japan buys more treasuries than China usually).