That's when dollars are taken away (blocked, frozen), then other countries will realize that you can have dollars and trade for dollars only as long as the United States allow it. At the moment, the role of the dollar as the world currency is already declining and will continue to decline, but as a convenient unit of measurement for calculating the value of goods, the dollar is likely to be used for a long time (well, like a meter, inch, gram, etc.)
This is logical, and the importance of the dollar in today's global economy is no secret. I see no indications of the possibility of abandoning the dollar soon, given the dollar's dominance in financial markets and the validity of the Bretton Woods Agreement, under which the world agreed to establish the dollar as the official currency for global trade. More dangerous than this is that countries no longer need a gold backing to mint their local currencies; all they need is a dollar reserve to be deposited as an alternative to gold. The world has entangled itself with the dollar, including countries that are not friendly to America and are now seeking to liberate themselves from American hegemony by ditching the dollar.
Returning to the Chinese-Russian example, have trades between them in local currencies succeeded? I believe this equation cannot succeed if we use the Russian ruble, because China has nothing to buy with those rubles if it sells its goods for them. On the other hand, trade in the Chinese yuan would be beneficial for both parties. But how long can Russia tolerate selling its products to China for yuan, which it is forced to reuse to purchase Chinese goods only, since it cannot purchase anything on the global market. The issue is very complex and all we see are attempts and not solid projects with a clear vision.