Good thing, then, that the politicians who engineered this collapse will all be dead and gone by the time their children have to live through it!
CNY does not freely flow across the Chinese border, and the government will not hesitate to put strict capital controls to limit inflows and outflows. The government knows that this prevents it from being used as an international reserve currency, but they would rather keep stability in the Chinese economy.
USD is not controlled in this manner, which makes it pretty easy to obtain. One of the important features of a reserve currency is easy obtainability and convertibility, but this runs counter to China’s internal stability goals.