If you're still on Windows 7, Microsoft will be ending support for it in 2020. Organizations, however, can purchase an extended contract for support.
Through the way of extra dough, all of the sudden support will continue to provide paid support for Windows 7 until January 2023, including security updates. This scheme is called Windows 7 Extended Security Updates (ESU) and will be per device, also that contract price will increase each year. The Extended Security Updates will be available for Windows 7 Professional and Windows 7 Enterprise customers with Volume Licensing. Also, Office 365 ProPlus will be supported on devices with an active Windows 7 ESU subscription till 2023. Customers that are in the ESU program will be able to continue to use the Office suite this way.
Though Windows 10 is closing in, Windows 7 actually still has a market share of nearly 40%.