As someone who is primarily a reader / responder this seems to be entirely positive. I got on the waiting list as soon as I saw that there was one.

Thinking about it from a technical angle, ActivityPub seems to be able to support larger/longer pieces of text (type "note" vs "article" in Activity Streams 2.0) so they can be passed, but instance admins might choose not to accept them, so authors are faced with creating a 500 char 'note' summary. From the spec, it looks like an “article” with summarizing “note” can both be part of a “collection”, but as to whether a Mastodon instance admin can choose to federate one element of a collection but not the other? It’s open source, so I could probably figure it out, but as Medium pays authors I don’t see articles being given away unless the author decides to do that — so figuring it out seems pointless.

As I see it, the primary danger is that other Mastodon users see article summaries as advertisements for Medium and complain to admins who in turn defederate. Maybe keep that in mind before adding some kind of tag like “click here to subscribe to Medium”.

As usual, just my $0.02.