This coming "Patch Tuesday", January 12, will represent the last batch of updates for Windows 8. After that, it is considered End-of-Life, and no longer supported. So any Win8 users should upgrade to [at least] Win 8.1... and if you wish, to Win 10.
Those still clinging to Windows Vista can count on more than a year of security updates, until April 11, 2017, and anyone running Windows 7 can do so with confidence until January 14, 2020. Windows 8.1 reaches the end of its Extended Support phase on January 10, 2023.
http://www.zdnet.com/article/still-running-windows-8-time-to-upgrade-or-else/