It really depends. Some governments do not want multiple currencies that compete with the currency it controls. It threatens the governments financial control. On the other hand, some countries could care less, especially the ones that are not tecnologically advanced.
That was the case with the Venezuelan government when they decided to crack down on those that were mining bitcoins in the country, even with all their efforts, people are still mining bitcoins, nothing can really bring down completely even in the case where they ban it and the value plummets, it sure to rise up again.
Banning a currency and manipulating its price are two very different things. It is nearly impossible to successfully ban something that by nature is decentralized. But if they tried to actually destroy the currency then that is possible but like I said earlier, very very unlikely.
I only started this topic to see what others thought of this idea.