I keep an old iMac in the studio storage closet with the old Firewire external drives just in case of a catastrophic failure of systems. If that ever occurs I can boot up the old system and keep the work flowing until new computer and any needed hardware arrives and gets configured. It would mean going back to 2012 platforms but they work fine within their equipment domain.
Haven't needed it yet but one never knows. I did end up digging out my old analog phone hybrid a few years back when an ice storm blanketed the city and shut down business for several days. I got an early morning call from one of my ad agency clients asking if I could help them due to their in house studio being out of service due to the weather. They had a client who needed to call in his VO part for a radio spot. So I said yes and went to the attic. I had the old phone hybrid boxed with some other old gear, retrieved it, split some phone cable into pigtails, ran an RJ11 from the wall socket and pigtailed the other end to the connectors on the hybrid, and ran a quick test. It sounded great! An hour later the guy called in and I got him recorded, edited, and sent the audio to the agency's audio editor who was working from home. He had everything he needed to get the spot out the door except a phone patch.