China hasn't figured out how sanctions, financial pressure (sabotage) and the application of military pressure which props up, and backs up the US dollar.
When China has military bases all over the world, dark sites near uncooperative countries, CIA meddling in all foreign governments, economic hitmen forcing the use of US dollars & loans or else, and occupying other countries with force for decades... Then when they outlaw a currency it will stay outlawed.
China isn't there, yet. And, they never will be, because WWIII would be instigated first... By us.