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.
I definitely agreed with you that bitcoin is too volatile to be used as a national currency , bitcoin being volatile will cause inflation in that particular country that adopted it as a national currency and coupled with the fact that bitcoin is decentralized I.e it is not controlled by anybody will even makes it much more difficult to be used as a national currency ... But the other side of my opinion is,there is a big possibility that the bitcoin will become a national currency. Aside from its popularity, it has an advantage from other currency because of it's amazing features that no other currency has. And that features may be the reason for it will become a national currency in the near future ...