It goes without saying that governments should stay away from our lives
But that doesn't mean that folks cannot be forced to pay Bitcoin related taxes (including an income tax). First of all, governments would have to legalize Bitcoin first since you obviously can't levy taxes on something illegal (that would mean legalizing it indirectly). Further, governments may put stricter rules on banks in terms of tracing money flows. In this way, you may have to explain the origins of certain monies which came to you bank account (when you cash out) and whether you paid taxes if you claim that you earned these sums from your operations with Bitcoin (e.g. speculation). Otherwise, you will have to think up something plausible to explain their source, which may not be worth trying (if you get caught lying, paying taxes may turn out to be a better option after all)