Bitcoin, for now, is not suitable to become a national currency of any country. Bitcoin's value is too volatile so a product or service will always change in price with respect to the price of Bitcoin. Also, a transaction fee is there with every transaction, this is not practical in using in a daily basis. It will be hard for the government to control the scenario. So if a country will make Bitcoin as its national currency then they have to regulate it first.
Before a government consider bitcoin as a national currency, they must replace first their existing currency. And that would be a drastic change specially on the market system. That kind of change needs a lot of research and market analysis because of the properties of bitcoin that will surely make a remarkable impact in the economy.
Of course, the government can't change the monetary system easy like many people thought. There're many people forget Bitcoin becomes the new monetary system still has many problems at current. Especially about the transaction fees and use without internet.