The decline has been going on for about 6 years in my household. That was when I last had to do a desktop/laptop tech refresh for my extended family and friends. I was spending about GBP8k a year with Scan before then - now I probably spend less than GBP100 a year.
Repairs often use secondhand parts from the spares box or eBay - when the originals are no longer made. Moving to a new motherboard for a Windows user generally would mean purchasing new copies of an O/S and Office too since MS made their licences more restrictive.
My small stock of W7 licences plus LibreOffice will handle some catastrophic conditions - but when that is exhausted then my aim is to move users to Linux Mint.