I skimmed the other responses and didn't see this so my apologies of someone mentioned it, but I think it depends a lot whether we are talking about black and white or color. Color transparency is already in its death throes. Print film will last a lot longer but the selections are already down to a few, albeit wonderfully excellent, emulsions. I'd be worried about it too eventually.
Black and white is so much easier to manufacture in small lots that I am unconcerned. Besides Ilford, whom Simon called "robustly profitable" there are also small companies like Afox and Foma making good products. No worries about B&W IMHO.