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.
I agree to you that each of our governments are still on the process of recognizing bitcoin to it's deepest details and functions, so they can know if bitcoin really can brings such change in the future. But I hope they won't value the threat that bitcoin can bring, but rather to value the help it can bring to every people and just regulate it to lessen the threat it can bring on a country. Because also for me, they can stop bitcoin if they want through eliminating/removing all transactions related bitcoin.