There's a big difference between "over a decade old" and "50 years" though. I'm not contending that there's a sizeable amount of 10+ year old applications that

There's a big difference between "over a decade old" and "50 years" though. I'm not contending that there's a sizeable amount of 10+ year old applications that are still useful, but I'd wager that their number is inversely correlated with their age; and that 50 years is too long of a support term to be sensible. E.g. HTTP is less than 35 years old. And it's not just because the outside world is moving on, if you use a distro from 2000 for 50 years you'll run into problems in 2038 because it still uses 32-bit time_t.