In A New Premise I explored a cashless society and the ramifications. Here's the blurb:
In the near future a crisis erupts when terrorists change their target from buildings and people to the world money supply. They discover a way to duplicate all paper currency as well as credit and debit cards in a way that renders detection impossible. The markets are flooded with phoney products and chaos ensues. A new government emerges in the U.S. with tight control of economic markets, prices and wages. It introduce a new financial system using an implanted microchip. But is the 'grain', as the microchip is called, merely an implanted debit card or are there more sinister and hidden functions?
A New Premise follows five different people coping in a dysfunctional new world that seems to only work for the few elite.
It appears others are thinking along the same lines. There's a type of tattoo that can tell you, for example, if you've had too much to drink. It may be possible soon to share a remote control kiss by means of a special pad attached to your smartphone.
Implanted medical devices, like pacemakers, have been around for quite a while but nowadays Implanted devices can be connected to the internet to monitor and adjust pain relief for chronic sufferers. It has been postulated that the smartphone of the future will be implanted in your head. 2023 is predicted as the year of commercial availability.
Do we scoff at these predictions? Probably not. Technological change has been so rapid and so all-encompassing that we are prepared to believe anything is possible.
Is it desirable? Will it be mis-used for purposes not intended? Will our thoughts still be private? I worry about the law of unintended consequences. You could start researching that possibility here. Cane toads were introduced to Australia to control destructive beetles in Queensland sugar cane fields but became more of a problem themselves.