If you ever studied Macroeconomics, you know that deflation and the lost of monetary policy are the two things that can drive a country in a big recession and "limited supply" crypto is exactly that: deflation and loss of monetary policy. So, no stable government will ever give up their currency and allow bitcoin to be used in its place. When they will feel a real threat, they can easily classify its as a commodity and tax the hell of its appreciation (which it already does for any other assets like gold, land, or real estate) and may even tax the transactions (like HST tax). This will make crypto very unattractive and costly to deal with, leaving only China, Africa, and South America being the primary users.