No idea if this is feasible or not, but could the fediverse have an internal DNS-esque system where domain details could be updated to reflect communities moving?
Kinda,
So everything in the fediverse uses its https url as an id. To fetch the content after its been posted, a server needs the content to be live.
As a result, everything breaks when domains go down.
FEP-ef61 fixes this, by making objects portable, and making it possible for servers to request them from other servers.
If I understand correctly, as long as a post was federated to a given instance before lemm.ee shut down, the federated copy of the post should be discoverable by searching that instance for the original lemm.ee URL.
This search can be done manually, or automatically using tools like Lemmyverse.link or Lemmy Universal Link Switcher. Many mobile apps also have built-in "open in my instance" functionality.
Wouldn't editing the posts to change lemm.ee URLs to URLs of arbitrary instances run the risk of breaking these tools?
I always recommended LW because IMO explicit discussions about decentralisation (as opposed to a general statement that an American oligarch can't buy Lemmy) are counterproductive when on-boarding people.