For governments to willingly use bitcoins, they'd have to forego their ability to print money. Who would do that?
I doubt Controllers will willing forego control too. But thanks to evolution their fate is already sealed.
Once this truth becomes evident to them, then the game theory optimal solution becomes trying to get behind
BTC first.
changers become controllers
Controllers can stay in control unless their means of control is changed. (Some central banking families have maintained massive control for 300+ years.)