Some countries or government may  not be able to use the decentralized cryptocurrency as the main money of the country. However, bitcoin and other cryptocurrency can quite go in parallel with such national money as it is done, let's say in Japan. To stake on decentralized state coins will not be, however they will be able to use their consumer qualities. Most likely, the states in their interstate mutual settlements will use only centralized cryptocurrency, which will be more stable. it is a decentralized cryptocurrency, and first of all bitcoin, need to be afraid to rise very high in its price, if they reach high price values, inevitably at some stage panic will begin and this cryptocurrency will fall, down to depreciation level totally.