Sooner or later, cash will die, and sooner or later the cashless society will come.
There is no problem in the technology of cashless economy, and the security needs to be improved and strengthened.
But that's only applicable for a nation that is embracing the blockchain technology. And even if all nation will embrace it, the downside of bitcoin being unable to be access or make a single transaction when there is no internet connection is a big hindrance in the realization of a cashless society.