I've more than once seen a scenario of a 386 or 486 box somewhere in the corner of a server closet that has been running untouched and uninterrupted since the mid-90s, performing some absolutely critical process, with no one in the company knowing exactly what it is. Everyone who could've possibly had a clue has retired decades ago.

The only consensus is to never touch it.

This is more common than many people imagine. And it's a ticking timebomb.

However, it also speaks volumes of the sheer quality of old-school hardware (and software). Most modern stuff has to be replaced (/rewritten) every few years. But there is more COBOL code running untouched from 3 human generations ago that our entire societies depend on than most people would be comfortable with.