It seems logical if Threads focused on client-to-server interoperation first, since in theory that would allow more people to use third-party clients but not third-party servers so Meta gets a hold of all the unencrypted messages.
So, they are going to be part of the server-to-server Fediverse, and keep all of the juicy app data from Threads users to themselves.
I predict if they manage to be the overwhelmingly dominant platform in the Fediverse, they’ll keep it working. If they see another big competitor jumping in and taking a lot of users (or hell, if Mastodon starts to eat their lunch), I’m not so sure.