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
Things are just getting started, man. The dollar won't lose its dominance any time soon, but the fact that some countries are starting to get rid of it means it has problems, and many more will soon realize it too. In the history of currency, USD is not the only dominant currency in the world, before that, we also had other currencies but were replaced by USD. It can replace others, others will replace it, and nothing is forever. The United States is not the founder of this earth.