On October 30, Microsoft stopped selling boxed retail copies of Windows 7, but new computer buyers will still be able to purchase the popular operating system when it's pre-installed or bundled with a new PC. The cut-off date for Windows 7 shipping with new PCs is November 1 2014.
If you buy a new computer from Dell, HP, Lenovo or another PC maker, depending on the device, you'll still be able to purchase it with Windows 7 pre-installed, with just over a year of life left in the operating system before support begins to wane. You can also buy a "system builder" version of Windows 7 with any custom PC sold through a Microsoft-certified reseller, giving you a full version of the superseded Windows 7 without any pre-installed software.
Microsoft's Windows lifecycle fact sheet sheds some light on the future support cut-off dates for Windows 7. Mainstream support for the operating system will end on January 13 2015, so regular patches and hotfixes will still be released until then. Extended support, where Microsoft no longer accepts warranty claims and reduces its security patching frequency slightly, will continue until January 14 2020.
So if you're not a fan of Windows 8.1, you've still got just under a year to buy a new PC with Windows 7 on it and over five years until security patches stop; that's plenty of time for a newer, better version of Windows to be released.