Even if supermarkets cease supply of such items it is reasonable to assume that pharmacies will still stock them.
GF food items fall into a different category. Most pharmacies do not stock a range of gluten free items - they obtain them on 'as required' basis from specialist suppliers who hold stocks. The supermarkets' choice of gf flours, bread mixes, and pastas appears somewhat restricted, and arguably supermarkets are stocking such items to meet a demand generated by those who are not coeliac, but who may have chosen to 'go gluten free'.
What happens when the current demand generated by non-Coeliacs diminishes? As far as I am aware there is no commitment by any supermarket chain to stock gluten free items in the case of lower demand. In any case, there is already a reported tendency for supermarkets to offer gf products containing oats (and not all those suffering from CD can tolerate oats). Additionally, where is there any element of choice with regard to flours, bread mixes and pastas? Codex availability for those who can tolerate it? A choice of gf pasta shapes?
I believe that the writing is on the wall - when the current gf trend diminishes so too will the availability of gf products in supermarkets, and given that most pharmacies are not stockists of gf, there may well be little choice left.
Perhaps CCGs need to be asked what they will do in the event that there may be ever diminishing availability of basic gf items from supermarket chains given that it is understood that NO commitment to ensure supply at affordable prices has been given by any supermarket chain to the NHS, CCGs etc.