The difference is that the US is not an empire. It's an economic hegemony (if you're looking at it from a relative power perspective).

Its power stems from sovereign, contiguous territory with resources, or a network of global treaties both economic and military.

In contrast, Britain was a globe-spanning empire, which disintegrated with national independence movements.

The equivalent would be if California and Texas decided to split from the United States.

And as the quip goes... the next few largest economies, including China, are pretty incentivized to keep the global economy rules as-is, because they benefit.

De-dollarization is happening, but is going to be a slow shift, with an uncertain outcome.