As of yesterday, Microsoft has stopped selling Windows 7 or Windows 8.1 to system builders. The only way to acquire a copy of these operating systems now is to buy the dwindling stock still available online. Technically, most versions of Windows 7 were pulled off the market two years ago, but Windows 7 Professional was still cleared for sale until October 31, as were all of the flavors of Windows 8.1. The chart below shows Microsoft’s sales chart for preinstalled versions of Windows.
Windows 10 is listed as being supported indefinitely because, according to Microsoft, it’s the last version of the operating system they’re going to build. Whether that’s actually trueis a different question altogether, and I ultimately expect it isn’t. There’s a great deal of institutional expectation built into the idea of periodically updating one’s operating system, and Microsoft is the only company currently claiming its current OS is now a static flavor. Android, iOS, and macOS all still use version numbers, and I expect Microsoft will eventually release a “Windows 11” as well, even if it automatically extends upgrades to all current users of Windows 10.
After a number of fits and starts, Microsoft has agreed to fully support Windows 7 and 8.1 on all Intel Skylake and AMD Carrizo platforms through the planned end date for security fixes for those operating systems (January 2020 and 2023, respectively). Future platforms, like Kaby Lake, Bristol Ridge, and all future APUs from AMD will only be supported on Windows 10. We’ve previously discussed the long-term difficulty of keeping legacy hardware operational on unsupported platforms — the long and short of it is that while it’ll probably be possible to shoehorn Windows 7 or 8.1 on to newer hardware, it’ll get progressively difficult as chipset drivers change and new hardware capabilities are added to both platforms. This could be particularly problematic on laptops, where a lack of support for modern power management baked into newer chips could lead to poor battery life.