Bitcoin (capital 'B') can not be an effective national currency nor should it become one.
If Bitcoin becomes a national currency, the government cannot print it easily. It has to earn it.
It not as simple as it seems, quantitative easing is not the biggest problem for normal currency users they don't care.
In the long run it is economic issue, true. What is the most important is stability of the money, bitcoin with its horrendous fluctuation and explosive volatility is not good fit for national currency of any kind.
At least for now.
Yeah but we all know and expect that as the coin becomes more largely used and reaches widespread adoption that high volatility tends to become a past issue.