The system I have in mind is strictly volunteer-run, and it automatically balances the files so that it minimises rare copies.
You're right, though, long-term commitment is rare from volunteers. That's why the idea is to make short-term commitment so easy that you have a good enough pool of short-termers that it works out in the aggregate.
Eh I didn't really do any work, it's just a design right now, but I think it's a nice one. If any archive team wants to work with me on this, I'd be happy to make it a reality so we have a nice FOSS system for distributed, volunteer-led backups.
I suggest emailing textfiles, he'll know who to connect you with in ArchiveTeam, and if there is an opportunity to connect with the decentralized web folks at ia. Strongly believe your architecture is superior to filecoin and IPFS due to relying on torrent primitives.
(ia source of truth, storage system of last resort -> item index -> torrent index -> global torrent swarm)
You're right, though, long-term commitment is rare from volunteers. That's why the idea is to make short-term commitment so easy that you have a good enough pool of short-termers that it works out in the aggregate.