The fact that it's technically possible doesn't mean the banks will enforce it. The reverse is also true, if we do not offer the flexibility, someone else will

The fact that it's technically possible doesn't mean the banks will enforce it. The reverse is also true, if we do not offer the flexibility, someone else will (since it is technically feasible). However, most of the central banks we've talked to are looking at negative interest rates above a certain amount, not for all digital cash holdings, to discourage people from hoarding it.