Some countries that are not ready for cryptocurrencies will ban bitcoin, others will try to control the movement of coins by imposing their own regulations. Japan and other countries welcome and legalized bitcoin instead of banning it. In my own country, bitcoin is not yet legal but the government did not banned it and they've been studying the cryptocurrency for possible legalization in the future. If government ban the use of bitcoin, people might instead try to buy or sell coins in the underground exchanges.