A distributed system is different from a federated system and from my understanding, much more complex. If the proposal I submitted is implemented, then I think that would solve your concern.

Imagine !gaming@lemmy.ml and !gaming@beehaw.org follow each other via my proposal. A user who doesn’t know anything about that following relationship can post a link at !gaming@beehaw.org and it can show up in !gaming@lemmy.ml. If either community goes down, the other community should be able to maintain all existing posts. There is the question of what happens to users of the community that went down (they may not know about the other community and can’t visit the community they know about to check its sidebar because its down now)