Likely, what you have to consider though is in the instance of pot prohibition it doesn't only affect marijuana as a drug but also it's usage as medicine, industrial hemp and using it as a food crop.
A Bitcoin prohibition would have similar deteriorating effects.
I think an outright ban is not very probable, more something like a nasty poison dart.
For example, the government could require that all *merchants* process incoming payments only
through *licensed facilities* i.e. banks with infrastructure to
recognize and block certain blacklisted coins of criminal origin.
And use undercover cops to enforce it.
Regular persons would then be told by mass media to use the same facilities for
storage of their coins and for incoming transactions. This way everyone will be "protected" from "illegal bitcoins".