It's not impossible. There's nothing to do prevent that for now. But I don't think governments dare something like that. Because there are so many big investors who we call "whales". I think they don't let it be.
That question is impossible because even the government haven't enough knowledge about the technology of Bitcoin. They don't have any idea how it works and can be used in some site transaction. Also not only Bitcoin but to all cryptocurrency they have no rights to banned it because crypto is decentralized, In other words no one can control to crypto. Many people tried and even the goverment but in the end they not win.