Pingoiun
It may well come to that - I know some outfits who have a range of VERY old machines kept in use because of this problem - I'm talking about pre Windows 3, some AMSTRADS and even older - also the relevant ancient tape & disk drives.
Sometimes it's software, other times it's a database or a tape
Generally they're in a locked room just in case they go walk-about but every few months someone seems to need them. You could get the code rewritten but why bother - it works fine
They're certainly not connected to the internet tho'...............