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.
I agree that governments try to limit bitcoin if it extends but bitcoin experience suggests that other crypto-currencies may develop if bitcoin be limited.
well if governments will want to regulate bitcoin they will most probably ban all the cryptos that are possible
though i doubt that they will start doing that because people would be really mad about that in my opinion