Longer answer – Those communities, posts and comments will still exist on the other servers, but sadly interacting with them will not federate that data to other instances anymore, since the host instance is no longer active.
We got to see exactly what would happen a week ago when Beehaw defederated from lemmyworld. For us (on lemmyworld) it was like if that server had disappeared. Comments from beehaw stayed on the list, but new content from them (comments or posts) didnt show.
Short answer – nothing.
Longer answer – Those communities, posts and comments will still exist on the other servers, but sadly interacting with them will not federate that data to other instances anymore, since the host instance is no longer active.
So you would still be able to see the posts and their comments on other servers?
We got to see exactly what would happen a week ago when Beehaw defederated from lemmyworld. For us (on lemmyworld) it was like if that server had disappeared. Comments from beehaw stayed on the list, but new content from them (comments or posts) didnt show.