I personally doubt that the transition to a digital cash will happen anytime soon as there are lots of factors to be considered.
Due to the disparity among developed, developing, and underdeveloped countries, the latter two suffers from technological deficiencies and innovation as each country has their own set of priorities. In addition, the shift to a digital cash system implies that the platform used would be secure and tamper-proof in order to avoid loss of cash. Lastly, the presence of physical cash has been in existence since time immemorial.
The barter system of transaction slowly transformed to using coins which represent cash in the society. Despite the convenience of having digital cash to purchase goods, a shift to this kind of system will leave other countries behind.
Exactly. The transition process will be time-consuming and challenging as not everyone will quickly adapt towards digital currencies issued by mainstream governments. We will expect old people to continue using physical cash for daily payments. That's why I believe that phasing out physical cash will take a long, long time. Consider these moments as the last opportunity to enjoy privacy/anonymity via the use of physical cash. Once it's "phased out", the era for privacy will be long gone. Each transaction you make will be visible by mainstream governments and central banks. It'll be similar to credit/debit cards. At least, people will have an alternative financial system that's private, secure, and outside the scope of third-parties. Crypto will co-exist with CBDCs allowing people to enjoy true financial freedom. The decentralized and open-source nature of crypto/Blockchain tech will make this possible.
Nonetheless, time will tell us what lies ahead with the mainstream economy. While CBDCs are the way of the future, some governments have been reluctant in accepting change. Most third-world countries still rely on physical cash, without any indications of adopting digital payments anytime soon. The lack of Internet access on such countries, greatly delays the adoption of CBDCs. If governments are still interested in making CBDCs a reality, they're going to need to provide citizens the tools they need in order to participate in the new digital economy. Just my opinion