I think they cant. Bitcoin is very successful and big industry beside there is no big effect of it to the real world but make the people grow. In short there is no bad reason to totally ban bitcoin.
They can't kill bitcoin, even if they try ... Fans of cryptocurrency fear government regulation could ruin it, but they shouldn't be concerned. ... As governments struggle to ban technologies like Tor and encryption, it seems impossible to imagine them gaining the ability to truly impact bitcoin.