I'm a Mac guy for all intents and purposes, but I have a bunch of Windows boxes at work that run scientific instruments that I can't realistically upgrade. I have Windows 7, XP, 2000, 98, and even 3.1.1 all in service and operating. I operate them strictly offline, and don't worry about running obsolete OSs on them.
In fact, the last I checked, I'd have to spend a big pile of money to update things like my newest GC-MS, an Agilent 7820/5975 that's run by MSD Chemstation E.02.02. Agilent is very adamant that it won't work on Windows 10, and folks I know who have tried say that it's not true(it won't work on an out of the box Windows 7 install from what I understand either). The solution is to upgrade to their newer software, which would be several thousand dollars.
One of my more recently acquired items is a Varian 3800/300-TQ GC-MS, and the software for it is on XP. Varian is long gone, and the current owner of all of their IP, was nice enough to send me a big pile of service documentation for this including all the internal Varian service bulletins. Varian closed up shop in 2010(sold out to Agilent) but the last couple of service bulletins I have dealt with Windows 7 and basically concluded with "don't even try it."
So, for various reasons, some of us need to continue using obsolete versions of Windows. If you're using them offline, there's no reason why it's really even a problem.