Earlier quoted context omitted.
Windows 7 is already out mainstream support and has only 3 years more of security patches. Unless you are telling me you are one of the very few people still on Windows 8.1, now is as good of a time as any to plan for a migration to Windows 10.
At my workplace, most users are on Windows 7, and few on Win 10, and fewer (if any) are on windows 8.1 Migration to windows 10 is not going to happen until it is absolutely necessary.
Even Windows 8.1's equivalent Ubuntu 14.10 (Utopic Unicorn) fell out of support two years ago. Though arguably that's intentionally unfair because Ubuntu 14.04 (Trusty Tahr) is the closest LTS and still has support for less than two more years (through April 2019). Though that's quaint in comparison to Microsoft's generous extended security support of Windows 8.1 until Jan 2023.
The reluctance to migrate users by corporations creates its own worst enemy. The longer you wait the tougher it is to migrate, the more versions you skip in the middle. That's both a detriment to user learning (they miss transitionary learning steps and evolutionary UX migrations), and a one of those "doctor, it hurts when I migrate because I do it so seldomly, so I migrate less often and it hurts more" problems. The less often you distro upgrade the more problems you have so you loathe to distro upgrade creating more problems. Maybe distro upgrade a bit more often? I realize that is a radical assertion in modern corporate IT, but it seems like a common sense one.