There are lots of computers out there that are still running Windows 7 even though Windows 10 has been out for a very long time and is now installed on 700 million devices globally. The reasons for staying on an old OS like Windows 7 are many and varied but some folks just feel their OS is working just fine and many end users don’t want to shell out money to replace something that isn't broken. In the enterprise realm, it can be a huge undertaking to move hundreds or thousands of PCs from one version of Windows to a new version, especially if there is proprietary software or apps that might have issues on Windows 10, though few would argue that security is paramount.
Microsoft has previously vowed to offer Windows 7 extended support through January 2020. After that ended, the expectation was that no more security updates would be offered for Windows 7. Microsoft has now stepped up and noted that, despite the end of service
The caveat is that the updates past January 14, 2020, will be sold to users on a per-device basis. The price to buy those updates will also increase each year. Extended Service Updates will be offered to Windows 7 Pro and Windows 7 Enterprise customers in Volume Licensing. That means some Home version users won't be able to get the updates. Customers with a Windows software assurance plan in place will get a discount on the updates along with discounts on Windows 10 Enterprise and Windows 10 Education subscriptions. Customers who pay for the Windows 7 updates will be able to continue using Office 365 Pro Plus.
Microsoft has also announced Desktop App Assure service from Microsoft FastTrack that is intended to address issues with Windows 10 and Office 365 ProPlus app compatibility. Microsoft says that Apps that work on Windows 7 will continue to work on Windows 10 and all future feature updates. Microsoft also notes that this service is part of its commitment to eliminate app compatibility as a roadblock to migrating from Windows 7 to Windows 10.