The first question a headline like this comes to mind is : What are those PCs (including laptops) being replaced with? Obviously a PC/laptop can only be replaced with another one. So the aggregate demand generated by replacement needs cannot change drastically over the years. I assume this part of the demand will stay somewhat stable with slight ups and downs. Then the other part of the demand is the demand for new laptops. Which also cannot change a whole lot unless there is a drastic increase in population. So the remaining part of the demand that happened due to remote work/class requirement - that may contribute to the decrease as demand for that wane as folks go offline again. But that itself cannot contribute to 75% profit sink. A headline like this does nothing but spread misinformation and I wish there was a way to legally ban them. At least HN moderators can do their part by not boosting these time of meaningless article by using a little part of their cerebrum cortex.
It's the equipment version of a "staycation" - you keep your older kit and save your money. Windows11 requirements are quite low (1Ghz/4GB RAM/64GB Storage). macOS has ever increasing requirements but there are workarounds to keep some older but not decrepit machines operable [1]. And there's always Linux for the rest.
Also just like cars - I'm sure the used market is thriving.