and they have to be stored on a medium that is long term
have lots of stuff on floppy disks, tapes, etc that, while
for intents and purposes inaccessible without a trip to the computer
museum. the format is only part of the issue.
Of course there are many interesting challenges at the level of storage
media. But I would dispute that your material is archived: an archive is not
the same as a pile of old stuff in the attic.