If you own a system with an Intel 6th generation Core processor—more memorably known as Skylake—and run Windows 7 or Windows 8.1, you'll have to think about upgrading to Windows 10 within the next 18 months. Microsoft announced today that after July 17, 2017, only the "most critical" security fixes will be released for those platforms and those fixes will only be made available if they don't "risk the reliability or compatibility" of Windows 7 and 8.1 on other (non-Skylake) systems.
The full range of compatibility and security fixes will be published for non-Skylake machines for Windows 7 until January 14 2020, and for Windows 8.1 until January 10 2023.
Next generation processors, including Intel's "Kaby Lake", Qualcomm's 8996 (branded as Snapdragon 820), and AMD's "Bristol Ridge" APUs (which will use the company's Excavator architecture, not its brand new Zen arch) will only be supported on Windows 10. Going forward, the company says that using the latest generation processors will always require the latest generation operating system.
Microsoft provided PC World a short list of approved devices that use Skylake processors that will continue to be supported during the 18 month window when running Windows 7 or 8.1. Those systems are: Dell Latitude 12, Dell Latitude 13 7000 Ultrabook, Dell XPS 13, HP EliteBook Folio, HP EliteBook 1040 G3, Lenovo ThinkPad T460s, Lenovo ThinkPad X1 Carbon, and Lenovo ThinkPad P70. In conjunction with the system builders, Microsoft will test those systems with Windows 7 and 8.1 to ensure that drivers and operating system fixes work as expected.
The company's official reason for this change is a little opaque:
At the same time, we know many of these customers continue to rely on Windows 7 for its well understood reliability and compatibility. Windows 7 was designed nearly 10 years ago before any x86/x64 SOCs existed. For Windows 7 to run on any modern silicon, device drivers and firmware need to emulate Windows 7's expectations for interrupt processing, bus support, and power states—which is challenging for WiFi [sic], graphics, security, and more. As partners make customizations to legacy device drivers, services, and firmware settings, customers are likely to see regressions with Windows 7 ongoing servicing.