«Installing fire exits in Bluesky» is one of those ideas that sounds good in principle, but completely trips over itself in practice. The comparison with the SMB/Samba situation doesn't even hold. Microsoft went to great length to preserve backwards compatibility to support older versions of Windows, so they couldn't just “pull the rug” from under the Samba dev feet easily (and not for lack of trying). BS has all incentives to do that if FOF becomes even moderately successful.

By the way, your explanation of what happened to XMPP inter-service, optionally encrypted group chats in terms of its adoption by the same businesses now entering the Embracing stage with activitypub is a good summary.