it's not as important which currency they use, or if they use multiple currency. they used the dollar, not because of the strength of the US economy, but more because of the stability of our politics. the strength of the dollar is a big +. it's more about what they have been doing with the money and what they intend to do. look toward the bottom of the article about policy toward developing countries.
if they dump the dollar it's probably not a good thing for us. we would most likely see our dollar devalued even more. that would hurt investment, and might even cause dollar dumping.
now, if they go to a newly made international currency, that's a whole new can of worms. i don't think that's exactly what they are talking about now, although i have heard it mentioned. that would be the scary, one world stuff. what would back it? how would you determine the value of a magically manufactured currency?
economics tangles my mind. it's to mathy.