All computers will die of old age at some point. It’s not always the OS that’s the problem. If you have an win7 machine you’re going to have age issues that will kill it at some point and you will lose anything that’s not backed up.
While technically true, in that hard drives will eventually fail, and you could have another physical hardware failure, unless you have a program that requires some capability that the newer CPUs provide, your computer should easily last 10 years or more. The horsepower available these days in PCs is way more than the average non-gamer will ever use.
I recently had to finally bite the bullet and upgrade my desktop because a program I need to use, and need to have support for because of my job (VMWare) no longer supported the CPU that I was using because it makes use of some of the newer virtualization features of the newer processors. My old computer was just shy of 10 years old, and was still working fine, but then, I'm using Linux on my desktop rather than MS-Windows so it doesn't just slow down with time, as seems to be the case with Microsoft operating systems. I fully expect the new desktop I built to last 10 years or more, because I buy just a hair below the top end of processor line when I build. Given my configuration, it doesn't get stressed out at all until I'm running 4-6 virtual servers in my VmWare environment, and even then it's mostly memory constraints, not a raw horsepower issue.
Most home users who are not running modern games or hardcore 3D graphics modeling or something like that should have no problem continuing to use older systems.