I think you are overlooking some serious changes to the way the Fed regulates the money supply in the last five years. They are printing over 85 billion dollars every month. The stock market is soaring... why? because the government is artificially controlling interest rates which makes the value of your dollars go down fast- so people are forced not to save their money in a bank account but instead put their money "into" the economy- wealthy people are putting it into hard assets, and people that don't have as much are dumping money into the stock market as a hedge that their savings is loosing value every day. The result is a market that looks like it is doing great but is quiet volatile itself.

I agree that we should be very careful to just suddenly start running around yelling "the sky is falling" but I have heard an economist at the Fed (during a banking townhall) say "We are in totally uncharted territory" referring to how they will pull back all of the liquidity they have pumped into the market.

As for your comment about the US government saying "Use US Dollars or else..." that may not be the way that it looks on the surface but the US Government is very heavy handed in how other countries are allowed to control their own currencies, how multilateral trade deals are written in terms that force other countries to give up control over their own monetary policy.

You are correct that individuals around the world views the US dollar as stable and prefer to keep at least some portion of their wealth in US backed treasuries- but I would caution anyone from thinking that this is a foregone conclusion.

The fed uses a few people to try and hit multiple targets all at the same time... they have to deal with a bureaucracy that favors age and longevity, they have political pressures (see the Greenspan article above), and they have to make certain that their decisions keep their institution (coincidentally not a gov't institution but a private company)alive. The Fed is first and foremost a US-centric org. Whereas cryptocurrencies use the global market to find their level- whatever people agree is the price is the price... set number of bitcoins, completely liquid, and can cross borders without blinking... making trade easier than has ever been imagined before.