Lots of predictions don't come true. The dystopian "A Nice Morning Drive" from 1973 turns into the Rush song "Red Barchetta" in 1980, and 40 years later, it hasn't happened.
The 20 year old prediction wasn't that in 20 years cash would be banned. It was that eventually it would be banned.
And yes, you can look no further than this thread to see that it is being either banned or severely limited around the world already.
Gov: "There will be no app to restrict your movements if you aren't vaccinated."
Six months later: there's an app.
Gov: "The vaccine is fully tested and is completely safe"
Six months later: vaccine turns out to not have been completely tested, and the corporations behind it can't be sued.
Consider me heavily, heavily sceptical about CBDC's and the government's/central bank's desires to build a social credit system. I've seen too many quotes by August Karsten not to be.