What legacy apps worth keeping “documents” for - I’m assuming non game apps — would be worth supporting? The chances are even if they did provide support for 32 bit abandoned apps, they would break sooner or later with a future OS upgrade.

Besides are you planning on keeping the same IOS device forever? The newest processors are 64 bit only. I doubt that Apple will ever release a new device that will support 32 bit devices - except for maybe a new iPod Touch or iPhone SE.