Cash is king let us never forget it. Cash has always been the primary form of payment. It was until very recently accepted everywhere. Most likely will once again be accepted everywhere especially given the need to make sure we do not disenfranchise the unbanked and underbanked will remain the default form of payment
This said, what always amazes me is how so many authors forget Apple Pay, Google Pay and the other NFC based mobile phone based payment solutions are simply another device capable of carrying your debit and / or credit card credentials.
What many of these authors are starting to remember is how much it costs a merchant to accept these alternate forms of payment. I wonder when they will also begin to appreciate how many if not all of these alternate forms of payment only work when the power is on. Our always on society assumes power never goes off. We dream of everything in our mobile phone and forget when we last could not use our phone because the battery was empty. Or the store clerk who could read your card because the power went down.
This is one of the redemining facts about cash. Cash exists without power and can be used whenever.