Many states have already legalized the crypto currency, but made it property, not a means of payment. But this did not affect the work of bitcoin. Difficulties in working with crypto-currencies arise only in those countries that have banned the use of crypto currency.
Yeah, a lot of states have legalized it for now and some are simply just quiet about it and I believe their idea of legalization would bring about some form of regulations and then when it comes to making transactions with the use of fiat, there would always be a need for fiat, and that certainly should make it not a threat to the government.
Even when we start hitting the point of real life usage, some of these tools will have a way of sticking with regulatory policies and comply and in that case, being a threat to the government will really not be a problem. If it is a huge threat to the government, we all know the government will frustrate and jeopardize everything.
I do not think governments are threatened by the fact that we are starting to use cryptocurrency. Any smart government would react and adapt. They can have their own tokens or coins and even if not that they can just start to tax bitcoin and other crypto currencies in a smart way and even manage to create a governmental protected wallets and exchanges that can really make them richer.
Think about it, "wallet" is same as insurance business, wallet websites hold your coins for you until you need it and they can do whatever you want with your money as long as they still have it when you want it back. Perfect chances for something as big as a government.