I say government can ban bitcoin and they will do it. Here is how:
government asks everyone to "buy bitcoin". If everyone tries to "buy bitcoin" the blokchain can not handle everyone so there will be such a huge backlog and bitcoin will quickly be banned! problem solved.
here is a demonstration
Source http:/calvinayre.com/wp-content/uploads/2016/07/trump-presidency-will-shake-markets-cause-surge-in-bitcoin-price.jpg
or maybe not