I doubt if the government of any country can adopt cryptocurrency as their legal tender in the country. The maximum they can do is to adopt the blockchain technology in solving some paramount problems. Adoption of cryptocurrency will make them lose the power to monitor monetary policies in the country and no country can afford that.
True, every country really needs to monitor their monetary policy, so if you want to adopt cryptocurrency, you have to be able to sort it out, while things to monitor monetary policy are also needed by each country.