While bitcoin might continue, most citizens will stop bothering at that point because buying or selling bitcoin shows up in tax audits.
The government can also make it illegal to operate a bitcoin node or transmit bitcoin transactions, including for ISPs, which would get the protocol quickly blocked.
Additionally they could rule Bitcoin to be an illegal form of monetary exchange which would mean that anything you buy via bitcoin would get you in hot water in addition to the tax problems if you can't prove you used a legal monetary method.
Of course, some people might use Tor and somehow manage to get money extracted from the Tax system so they can buy bitcoin without their local tax office knowing... but how many of the Mr. Normal population are able and willing to do that for bitcoin?
I think you severely underestimate the power of the government.