In many ways, a blockchain currency is the ideal form of money for a country.
1. Every single transaction is recorded, no matter what. This is a huge advantage over cash.
2. Relatively cost-efficient (e.g. a US penny costs more to make than it's worth). Compared to having to re-design and re-issue anti-forgery bills every decade or so.
3. Safe as long as it requires multiple identification.
4. Could be designed to be instantaneous and only require internet access.
5. Supply/demand/mining power could be tightly regulated and micro-adjustments can be made.
The only cons (for the govt) I can think of is that it requires a deep internet/electricity infrastructure to be widely implemented, and that it might compete with the existing currency, and the older generations would have to be taught. For citizens, the pro's would depend on what design it takes and the con's would be loss of privacy on your finances.
In countries like South Korea (where more than 50% of the pop live in cities) or Singapore, cryptocurrency wouldn't be difficult to implement. Many of these countries already use e-cash for public transport, ect.
I doubt that a nation would adopt an outside currency but probably would be willing to create their own. Could they completely control such a system, would it succeed, and would it be good for the current community?
Ya right now many nations are beginning to develop e-cash transactions to make it easier, but only as an alternative fiat. The use of crypto on a nation must also need further study for consideration of better and more mature. Although there are some ideal form, as you say but crypto still have big risks, like the risk of hack and user negligence resulting in the hard disk or server storage of bitcoin is damaged or accidentally erased. Good effect if the nation is to control a crypto is certainly clean from money laundering, while bad effect that maybe some people do not like is the increased cost because it will be taxable. Good or bad maybe each country is different because of the conditions of each country is different, including economic conditions and developments.
