A few countries and central banks have been talking about digital currency, and most of them are carefully ignoring the term crypto. Fact is- digital currency is not the same as cryptocurrency. These countries/central banks are recognizing the benefits of the digital currency features of cryptocurrency, but they dont want any of the decentralized uncertainties that come with blockchain-based currencies.
Will countries or central banks create their own cryptocurrency?
The main peculiarity of cryptocurrency is that it can be mined by anybody and almost in any place having Internet connection. These very efforts of thousands of miners give the actual value to crypto.
Image that a bank decided to invest in mining equipment and issue their own money - will they be as anonynous and demanded as conventional cryptocurrencies? No. So that's actually the answer to your question.