Nano-SIMs are being stockpiled by European networks

[inquisitor]

Actually after realizing that the difference in thickness between 2FF/3FF and 4FF is 0.09mm (approximately the thickness of a human hair) I think even 2FF and 3FF SIM cards could be forward compatible to 4FF as you can cut them in height and width and, as NFH does, I also doubt SIM slots of 4FF phones will be manfactured with such high precision that this marginal difference in thickness of SIM cards will have an impact. Anyway I still dislike this new attempt of Apple and operators to establish some exclusivity and hinder people from swapping SIM cards between devices. The decrease in volume is a ridiculous argument I think.