All current limitations of Bitcoin aside, remember that the entire system is ultimately dependent on Internet connectivity. Any grand plans for nation state adoption require broadly deployed Internet service. Yes there are technologies that address this but they are quite immature. Just saying, it needs to be considered as a factor depending on who you're talking about. Cyprus, as an example since it's the favorite mention du jour, does not have very good Internet service on the whole. In fact, it's quite poor.
That's an interesting point. I would add, though, that there already much, much more internet connected devices than bank-connected devices.
Furthermore, the national crypto currency does not need to replace paper notes, and paper notes can be used for small amounts where no Internet connectivity exists. Just like today with fiat currencies...
The troubling part of this national crypto-currency scenario might be with tax and accounting laws.
Would the "clever" country demand from its citizens that they declare the full list of their crypto-currency adresses, allowing the tax services to monitor each and every digital money transfer ?