ays someone who has evidently not spent much time in the IT industry, let alone software development.
"dictated obsolescence and cessation of support" is a nonsense that only uneducated consumers spout out
Odd that the software I wrote was certainly in use 20 years after it was written, and there was even then little prospect of it being replaced.
IT is complex with a rapid pace of change, all parties involved have to continually adapt to new developments (and new requirements from customers). Developing software costs a shedload of money, maintaining software costs another shedload of money.... you can't support it all for ever, it simply would not make a viable business model.
In the world you describe most customers are best advised to find a good model and stick to that model for 10 to 20 years ie only change product when there is good reason to change.
You also appear to be overlooking the fact that support costs after ten years are likely to be pretty trivial.
The reason for my original question was that I would expect any end-user buying thousands of computers to insist that software support continued for 20 years. Assuming that a few buyers have shown that level of common sense then the additional cost of providing support for everybody is negligible. In fact, ceasing support becomes a marketing decision.