A Haswell-based system running Win 7 and serving as a small server is working perfectly. And when I say perfectly, I mean it doesn't even log anything more than an informational message in the System Event Log for months at a time.
It runs forever without fault, does its job with aplomb, has plenty of free storage, and will not likely be asked to do any more in the next few years than it already does. It's layered with much more (and smarter) than typical security and its usage is such that it's not at risk from typical things like web pages loaded into a browser and downloads by a user. Likely it won't need updating until the hardware actually fails. Since it's high quality server hardware, that won't be for years.
So... To update it or not? I'm seriously leaning toward not. Ever again.
My father tried to teach me, "If it works, don't fix it".
I'm knowledgeable enough about networking and OS operations that I'm not affected by FUD and hype such as "OMG, if you don't update you'll be infected for sure". I know how it could be attacked, and it's just very, very well protected.
I always try to keep in mind that Microsoft hasn't fixed anything since Win 7 went off mainstream support, and the only thing they've done lately is to slow the OS down... Even if the heaviest patches are disabled (GRC InSpectre, anyone?) it's still slower than it was in 2017.
I can't believe I'm even considering whether to run another Windows Update on it. The social engineering that has brought us to this point and made us feel dependent on Mother Microsoft to keep trickling out fixes for vulnerabilities they originally built in is mind boggling.
What price, (a false sense of) security?
-Noel