Microsoft announced earlier this year that support for Skylake processors in Windows 7 and 8.1 would be quite limited: compatibility, reliability, and security fixes would only be offered until July 17, 2017. After that date, only security fixes would only be made available, and those security fixes would only be created if they had no implications for the compatibility or reliability of others platforms. Full support for Skylake processors—and its successors—was only to be offered to Windows 10.
Perhaps unsurprisingly, this has resulted in some pushback from enterprises, and Microsoft has shifted its policy in response. The window for compatibility, reliability, and security fixes has been extended by a year to July 17, 2018. The limitations on security fixes have also been removed; now all security fixes will be made available—until January 14, 2010 for Windows 7 and January 10, 2013 for Windows 8.1.
Nonetheless, Microsoft still asserts that Windows 10 is the best option for new systems. Installing Windows 7 on a Skylake system can be challenging; Windows 7 has no built-in support for the Intel integrated USB controller (so booting from a USB stick to install it is difficult) and no built-in support for NVMe storage (which is increasingly an issue in laptops). It also cannot take advantage of Skylake's new power management capabilities or use virtualization to improve security. Windows 10 is still set to be the only option for the next generation of processors, including both Intel's Kaby Lake and AMD's Zen.