i think government could kill and stop bitcoin if they want and they can do it as fast as they can because they have unlimited source to do this. but i think the government will thinking to not stop or kill bitcoin and i think they are now is study about bitcoin, they have many questions about bitcoin and they need the answer. so they let us to still use bitcoin because they know that they can learn bitcoin from many ways and they want to see how bitcoin in future.
Powerful governments are able to do anything so in my opinion they will be able to stop or kill bit coin if they want as they have unlimited powers but I dont think that governments will take this step because bit coin is getting more popularity day by day and its prices are rising high which is very profitable for the investors and also for the economy of country.