Without the Petrodollar, the USD would already be dead. The day the OPEC will start to accept selling petrol for something else than USD the things will start to change. And that's the only thing China is waiting. They do not import from the USA, they do it from Russia, Irak, Brazil, etc.
Another fact to consider is the commercial war USA/China

Also, the USD is losing power as the first foreign currency for 2 decades and it won't go better
With all this, when the dollar will lose its value and people won't trust it anymore.who will be interested in having and using this currency? nobody.

For China, it's in its own interest to not rely anymore on USD but the country won't get rid of the USD before all this happens.