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.