At present, the global bitcoin transaction volume has reached more than 200,000 daily, and the number of merchants accepting bitcoin payment has reached several hundred thousand and is growing rapidly. In some developed countries, using only Bitcoin already meets day-to-day needs. It is believed that in the near future, Bitcoin will become the mainstream currency on the Internet. But it will not become a legal currency.
I think it's impossible to make Bitcoin as country's currency because of its unstable price. Also as we all know that Bitcoin has a limited supply unlike fiat. Bitcoin only be an alternative money but can't be the country's currency.