The interwar era between WWI and WWII is most instructive for what a multipolar currency world looks like. The Pound Sterling still mostly worked before WWI and the Dollar rose in the wake of WWII.

The absence of a currency hegemon caused "Kindleberger problems," named after the economist who described them, and will cause them again. The big issue is that everyone wants to pump exports to pump their real economy, they can't all succeed because the world is a closed system, so they fight. First with tariffs, eventually with guns.

These Kindleberger Problems will get worse until the US gets its shit back together or China assumes the throne. Note that assuming the throne will destroy the export sector that they love so much (Triffin Dilemma), so not only are they not ready today, they don't even clearly want to be ready. Much like the US between WWI and WWII.

Buckle up, because the tariff wars, Great Depression, the economic driving force for the imperialism of Imperial Japan, and other awful things that you've heard of before all fall in the category of "Kindleberger Problems," are all downstream of not having a global currency hegemon, and are likely to rhyme with what comes next.