Maybe I was thinking a bit too far. NIP94 and 95 seem to be about targeted files. I was thinking about the main use case for filesharing:

Images and videos in your nostr feed. Currently I‘m signing messages containing URLs which may change the linked image in the future. The weakest link in censor resistance is then Imgur (or AWS). Signing magnet links (or generally content hashes) would allow clients to verify that the referenced image still is what I published in the past. Using BitTorrent would already solve this.

The problem I would like to solved though is one about hosting costs. Why should anyone seed your files? Maybe the clients could? This would be technically challenging, I guess. So I think it‘s more probable that nostr relays would run a filehoster sidecar and earn money from it.