Microsoft is really serious about the adoption of Windows 10. The company has used free upgrade promotions and obtrusive advertisements built into Windows Update to prod users into dumping older versions of the operating system in favor of the 2015 release. Curmudgeons clinging to Windows 7 will now have a tough time buying new PCs with the old operating system, as Microsoft has ended sales of Windows 7 Professional and Windows 8.1 to computer manufacturers.
Windows 7 Professional joins Windows 7 Home Basic, Home Premium, and Ultimate on the "no longer available" list, where the other Windows 7 versions have found themselves since October 31, 2014. Windows 8 has been unavailable to PC makers since June 30, 2016.
The move is part of the Microsoft's Windows lifecycle. Sales of retail copies of Windows 7, Windows 8 and Windows 8.1 have already ended. Windows 7 is now in its extended support window, set to last until January 2020. Mainstream support for Windows 8 is scheduled to end in January 2018, with extended support terminating in January 2023.
Microsoft has billed Windows 10 as the last version of Windows, and the company has yet to announce when the OS will stop being supported. Windows 10 was refreshed in last summer's somewhat controversial "Anniversary Update," while a "Creators Update" is set to be released some time in 2017. Microsoft's move may not matter much, since Intel has announced that new CPUs and chipsets will only support Windows 10.