@folkerschamel @mmasnick @mastodonmigration @mmasnick.bsky.social
Centralization is not binary the way you're presenting it here.
Let's say we have a 400M-user Threads and a 1M-user Mastodon. If they defederate or Threads dies, Mastodon users loose access to 99.8% of the people they could communicate with. Ouch. But Mastodonians still have 1M people in their network so maybe it'll survive. Definitely not certain, though, that's a big cut. That's why I say a version of the Fediverse with 400M actual federated Threads users would be quite centralized.
Now, people on one side may not actually give a shit about communicating with people on the other side. Fine, the people in both networks are not gaining a lot from federation. This seems to be more or less the status of most of the Fediverse and Threads, and why I think the correct thing to do is count the number of Threads users who have actually turned on federation, not the rest of them. If they defederate (as a lot of the Fediverse has done already), not a lot of connections are cut. This is why the existence of Threads does not increase the centralization the Fediverse today. This could, of course, change. This is why one should *keep* counting the number of Threads users who federate.
Now, let's do this for Bluesky and Blacksky (in its role as a PDS, appview, and maybe soon relay). If, today, they split (say, the Bluesky relay stops talking to the Blacksky PDS and appview) or Bluesky dies, the 718 people on the BlackSky PDS lose access to the 38M people on the Bluesky PDSes: 99.999% of the people in the network. Again, maybe people on Blacksky could care less about people on Bluesky. But, given the even vaster difference in size, I'd wager that Blacksky users are pretty strongly interconnected with Bluesky users. And again, maybe this changes; in the week I've been watching, the number of users on the Blacksky PDS has gone up by about 200. Maybe it continues to grow and gets a lot bigger, that would change the dynamic. So again, this is why it's worth measuring and watching.