Re: How long will it take banks to phase out physical cash completely?
Now the real question is, how long will it take banks to start the transition from physical to digital cash (CBDC)? Do you think that physical cash will still be used right after governments adopt CBDCs in their entirety? Or will it take decades before every single person in the world stops transacting with physical cash, paving the way for a full-fledged cashless society? Your input will be greatly appreciated. 
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.