Gov't will never adopt bitcoin as a common currency unless their economy is on the brink of utter collapse and they have no other option at that time. The main reason: They don't have control of it so they don't like to have total control of anything that their country has to use.
If the economy is on the brink of collapse, that is when they will try to stop Bitcoin at all cost. Think of Venezuela and all those high inflation countries. They are going all out to stop Bitcoin.