I believe we're pretty close to a single currency now. The US would never accept a currency which it does not control. The reason that countries like Canada keep their own currency is because it permits them some control over domestic monetary affairs, even if the international value of their currency is determined by what happens to the Greenback. I'm not with you here Keith because I don't believe there is anything that has absolute value.
National currencies have a given value as long as governments and central banks can maintain it.
The government and the Russian banking system had simply not done their job.