Les, it is not for you to decide when a particular item becomes obsolete. It is decided by the users on a case by case basis for each application.
It certainly isn't me and I didn't say it was, but it is equally certainly not, in any straightforward way, the users: the transition from obsolescent to obsolete is determined by the people who make the product and the people who provide the infrastructure support where that is relevant. If you could not buy film at all, film cameras would be obsolete. Wouldn't they?
Of course, demand and willingness to produce interact: Kodachrome, eg, had declining sales over many years because consumers - wrongly, IMO - preferred the saturated colours of Velvia, but the decision that demand was
too low to justify continuing production was made by Kodak. There were always people who wanted Kodachrome, and there still are, just not enough to satisfy Kodak. And if Kodachrome is not obsolete, what is?
To process Kodachrome you needed very expensive, proprietary equipment and specially trained staff, so it was only commercially viable to process it at all if volume was high. (You can process it as B&W, which is what most people buying it now do, and I have done it, but it is a PITA and after all the trouble it is a not very good B&W film). So it could not transition to a stable future as a niche product, as other things have - vinyl records, eg, or B&W film - although that
always results in higher prices. I don't know of any example of transition to a stable future as a niche product except on the basis of an open source platform, because otherwise the small producers who are willing to service niche markets cannot. The thing Nikon could do that would really help Ai and Ai-S users would be to make the F mount open source.
