Government only do things that will be beneficial for the citizens, they will have to evaluate to see if having btc as a means of payment will be good for the economy, I don't think it is all about the price but how the whole economy will fit into using btc,
I think the government are considering alot of things, aside from not able to have control, they will also think about the people and businesses and this will work.
I would like to correct the part about government doing it for citizens, there is a hierarchy of those that are benefiting from government decision, on the top is the 1%, second is those in power, those with some money, the citizen and then the poorest of the poor. If they ever lay their hands on bitcoin, the reason for that is that they want to control the transactions that are happening in their country, you do not want a rowdy bunch of citizens so you will put a regulation to help them to be put in their place.