Then clients could display a thing on the side saying something like: "broken link on the picture? try these other sources"
Of course this would be very unsafe, but better than nothing. Maybe just show trusted sources first.
Discussion
It will not be unsafe if each image/external reference has a hash, the the client can check If the hash matches before accepting the content
Hash should be flexible, so as to allow ipfs standards, torrent, dht, etc
no this is what caused ipfs to suck having too many options, just use a single hash function have a version so you can change it later, bittorrent only went to version 2 recently
with blake3 you can verify any chunk size from 1KB denominations