As the world knits into one global market there is a distinct disadvantage to maintaining your own currency (cost of battling fraud and counterfeits, support of rates, etc.), and many economc and political advantages to joining a common one. The three currencies will compete for members, "features," and political influence. The other currencies will disappear except in name.
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A count of independent countries in 2063 is made. Their currency backing is noted. Borderline cases are subject to the opinion of 5 independent economists, 3 of which are not from countries using the major currencies. A total of 95% of the countries must use one of three currencies on December 31, 2063.