I have less information about abroad but i must say something that we have to reason collectively,
Out of
195 countries in the world i know too well that most of the population (country's) are solely depending on USD, EURO, POUNDS, YUAN for major trade. I mean before anyone could trade among these 195 you need any of those currency to be able to travel across, and if only 6 countries decides to breakout from USD how do you think it will affect the US dollar?
There will be no much effects
I think the complexity of the global financial system and the dominance of the USD and other major currencies is not solely determined by practical needs, but also by complex economic and political factors meaning what it means. Any attempt to move away from these currencies will require significant coordination and collaboration. between countries, as well as careful consideration of the possible consequences.
While there won't be much effect I think any major shift in the global financial landscape will require careful consideration of the potential impact and a collective effort between countries to make it work effectively.