Yeah. The big issue here would be worldwide acceptance of a new cashless society, and the introduction of a global internet which anyone can get ahold of. As for old people, they're going to have a hard time getting used to making payments in a cashless way, as like you said earlier, they're more familiar with using physical fiat currencies.
But, I believe that we will get there someday with the introduction of cashless payments every step of the way. One thing for sure is that if proper steps are taken to ensure a great level of education for people to start adopting cashless payments, then a completely cashless society would come into effect in the future.
The most interesting part of a cashless society would be automation, as it would open up a world of new possibilities never before seen with physical fiat such as borderless payments, fast settlement, and the ability to self-fund bots and drones that would make most of the stuff we do nowadays.
If we combine the blockchain with smart contracts, IoT, and AI, we'll be able to see a world where anything could be funded with cashless payments in what we call an Internet of Value. Just my thoughts