In my opinion if a country fully adopted Bitcoin as its national currency it would definitely be a historic move. The transparency and limited supply could help reduce corruption and inflation but the volatility is a big concern, Day to day prices could be hard to manage and people with no internet or tech skills might struggle. It would push financial systems forward but also expose the country to a lot of risk So yeah it could start a new economic age but only if done with strong infrastructure and education in place
So far, we have 1 country that accepts bitcoin as currency and that is El Salvador. They legalized bitcoin as a major currency 4 years ago and you can check their current national status yourself.
I wouldn't call it a failure because it's still a legal currency there and they're still pushing it. But to be fair, things didn't turn out as they expected or as many imagined. Since the adoption of bitcoin, their economy has not really improved significantly and is still facing more challenges . Eventually, they were forced to turn to the IMF for loans to save their economies.