To be a realistic scenario the digital coins has to be very popular and unfortunately it not the case yet. And when we talk abount the economy of one country there can't happen things over night and in the end it will adapt.
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.
