Somewhere around the intertoobz, there was recently a story regarding a garage that had a tire balancing computer. It was a Commodore 64. I read another story yesterday about a Amiga 1200 running a modern RF communication system.
I think the upgrade/update virus has infected most of us. Me too at times.
And what happens when that C64 or Amiga dies? Right now, you could probably buy another one off of eBay, but do you think that one will last another 35 years?
I have a client who had been running a DOS app from 1981 that managed some industrial hardware. The computer was ancient, and finally gave up the ghost. Found out that while the software would run just fine in DOSbox on a modern pc, it wouldn't interact properly with the hardware it was supposed to be controlling. (something about weird signaling over the serial or parallel port). Found a replacement computer on eBay similar to the original to get them by, but then made it a high priority to get them the needed functionality from modern hardware and a modern OS.
No matter how much you think that you don't need to upgrade at some point, there's always something eventually that bites you in the ass if you don't.