Bitcoin will obviously improve the economy of any country if they have Bitcoin reserves aimed for a long term goal. But as a medium of exchange it won't improve their economy that much because they will spend more than the invested due to price fluctuations.
Depends on how much they are going to start with and what their target is at all.
To get a better picture and to see results, looking at the GDPs of some countries, there is much to be thought about and done..
In my opinion, Bitcoin is not suitable to be the national currency of a country. Looking at all the ups and downs of its price, Bitcoin’s volatility is too high and too dynamic. Such sharp fluctuations on the scale of a country’s economy can lead to serious risks and instability, which is too risky for maintaining the standard of living for the people. Therefore, Bitcoin is good as an asset, but it is not suitable as a national currency.