I had a job dedicated to this very thing. The company made the same light bulbs since the 60s with minimal changes. They ran into the problem of machinery becoming obsolete and my having to design new stuff to build the same lightbulbs
A previous job was with a defense contractor that made Klystrons, Traveling Wave Tubes (TWTs), and Microwave Power Modules (MPMs, a high voltage power supply, pre-amplifier, and TWT integrated in one case) for the military. Military projects typically have long development cycles and reeeeally long product lifetimes.
For MPMs, that meant the the first batch of fully functional prototypes got made and then nothing, possibly excepting a few repairs, for several years. Sometimes those several years were long enough that when a production order came there was a scramble to find equivalents for components that had been obsoleted, sometimes even including a printed circuit board re-spin. Then came several years in which hundreds or a couple thousand would be produced, and then production of that MPM model was stopped. After that would be years of ongoing trickle of repairs, and then ... maybe an order for another large batch and another scramble to find equivalents for components that had been obsoleted, and so forth.
Whether military or civilian industrial, equipment with life-cycles spanning multiple decades are a tightrope balance between keeping valuable assets in use and products in production, having to find sources of scarce parts or find equivalents that can be adapted, or buying new, expensive, equipment and figuring out how to integrate that into existing processes or equipment. With military grade semiconductors there are companies whose business model is to buy the whole line of equipment from On Semiconductor (Motorola) or TI for producing devices they have obsoleted and supplying those parts to defense contractors who are supporting or producing products with long life-cycles.
Because of their employment histories or sometimes lack thereof, not many DU-folk have experienced or cared about parts obsolescence beyond replacing their old PC/Mac or cell phone or washing machine (the ones who wash,
).