The Microsoft Exchange vulnerability debacle, which has been reported on to extensively by The Hacker
ITWorld has a very interesting long running series of articles chronicling the slow but steady demise of Windows 7 and the slow but stead rise of Windows 10 in terms of market share. Come January 14th 2020, Windows 7 support will officially end (unless you want to keep paying Microsoft for security updates on a per PC basis) and you will no longer get all of those critical updates needed to keep your organization secure.
What amazes me about the whole process is the prediction by Net Applications that Windows 7 may retain 10+ percent market share well into 2022, long after support has ended and almost every known flaw will be easily exploitable. Don’t get me wrong, I know first hand how painful it can be to update and replace thousands of physical PCs to get rid of an old OS but as hard as that may be, it is well worth it. In my own experience, the reduction in vulnerabilities just from going to a fully patched version of Windows 7 to a fully patched version of Windows 10 will make a world of difference on your audit scorecards.
Please do you and your organization a favor and move to Windows 10 now. You will be happy you did and it will allow you to sleep better at night.