The change in the economy won't take place overnight. It needs respective time space to grow and make a positive impact on the economy of the country. Governments fear that adapting bitcoin might affect the economy as well won't have control in hands. I believe more countries will adopt bitcoin seeing the growth that Japan has attained through bitcoin.
For now at least I think btc won't greatly impact economics of a country. Since it is just a currency, of would just be used as a payment processor and it really doesn't change the fact that citizen paid btc but have bought it mostly by using fiat. If there would be some effect, it would just open a new opportunity for citizens to earn money. It will only affect economics greatly if there are many whales in a certain country and if price is X100 higher than the current price.