There’s no need for the new Chancellor (I’ll update this with his/her name when I look up who it is) to panic and start hunting around for something else to tax get a couple of billion quid. The seigniorage will keep coming in for a while. A Gallup survey in the UK nearly a decade ago — Bull survey predicts cashless future in the Financial Times Virtual Finance Report. 3(3): p. 2 (March 1998) — found that two–thirds of people in the UK thought that notes and coins will not be needed in the future and almost half thought that notes and coins would disappear within a decade (one–fifth thought they would see the end of physical cash within five years). More surprisingly, four–fifths said they thought e–cash would be more convenient than physical cash even though none of them could possibly have used it. Yet a decade on, more cash than ever is in circulation — about £22 billion at the time of that survey to about £38 billion now — and the take from the stealth tax continues to rise (I don’t resent the money: after all, it’s not as if the government just wastes it).
These opinions are my own (I think) and presented solely in my capacity as an interested member of the general public [posted with ecto]