People will still find ways to circumvent this ban. In many countries weapons and drugs are prohibited, but they are used. The same will be with bitcoin.
It would be much easier than the ban on guns and drugs though, but if something like that happens, then the population of Bitcoin will gradually decrease, I don't think everyone will leave but there are some people who wants to go with government's many time without even understanding bans.
I don't think any government will ban Bitcoin.
i do not think that it will ever happen because the government have to understand the situation, they will surely take care of the emotion of the people because the trend of the people is now changing toward bitcoin.