I hate where this is going, but accept that it is inevitable. As much as I value my privacy, I've well and truly fallen into the trap of using tap and pay with my phone. I don't think I've carried cash in any meaningful quantity for years now.
Maybe it could be nationalised though, in the same way that currency is nationalised. That way the costs of managing it could be part of our way of life, not by a specific bank, or that datra being sold to various thrid parties.