Im thinking like an micro chip implanted in our body. This system is not out of the picture because how we discover things every year, it is not impossible that in the future this things may happen and it will boom like btc.
Of course this will be realized. Only this chip will not only be for payment, it will be multi-functional. In the world, the first chips for identification of a person are considered as a priority task for implementation. I think that the payment will be connected to it.
in my opinion, the other way to pay in the future does not need to be thought about in our enjoyment of this life, we see the current technology going forward and we do not have to worry about how it is already managed if you just need to use it, just wait