While standard support for Windows 7 was withdrawn some time ago, the operating system has still been receiving critical security updates for the past couple of years. These will be coming to an end as of January 14th 2020. This means that any new flaws will not be patched by Microsoft, leaving any computer still running Windows 7 very vulnerable to attack by hackers.
While the risk is unlikely to increase immediately, it will increase very quickly once that date passes, and there will be very little that can be done to mitigate it short of moving the device to a newer version of Windows. Even leaving just one machine running Windows 7 on a company network puts more up to date machines at risk, as once someone has successfully compromised the Windows 7 machine, they can then use that to gain access the rest of the network.
From January 15th, anyone still using WIndows 7 will start seeing full screen messages letting them know that support has ended. According to Statcounter, usage is still hovering at around 30% of all Windows users, so there's going to be a lot of people seeing it!
As usual, our advice for anyone still using Windows 7 to make immediate plans to move to Windows 10. If you have an application that can't be run on Windows 10, even inside an isolated Windows 7 virtual machine, then while you are making plans to remedy this, ensure the Windows 7 machine is removed from both the internet and the rest of the network it is on, and don't use USB sticks to move data from this machine to others.