Just around 24 hours after Musk made his comments, more than 42,000 new users joined Bluesky, making it the biggest signup day yet for the currently invite-only platform that launched earlier this year.
Bluesky saw a total of 53,585 new signups by the end of Tuesday, September 19. The new users gained in that single day make up 5 percent of the platform's entire user base of 1,125,499 total accounts.
The new user signups are tracked via the third-party website "Bluesky Stats." Looking over Bluesky signup numbers on the tracker for the past month, it appears that the platform usually sees from 10,000 to 20,000 new signups per day. Bluesky has doubled its usual daily new user numbers already, with many more hours left in the day still to go.
It's impossible to know whether Musk's comments about charging users to post on X really played a role in this, but it almost certainly had some effect.
From what you say I can approximate how it will go. First perpetual in-dev federation, then once they get enough people, they will say "not enough interest in federation" and stop development or pull the plug completely.
Except federation is already functional with 3rd party implementations. Sure it's possible they would choose to diverge in the official implementation in a closed branch, but that would not stop the rest of the clients from working. It's like if the biggest Mastodon instance went proprietary and shut down federation, the people who care would leave.
The main things they're working on are moderation tools suitable for federation as well as scaling