XMPP is alive and well, you can use it, many do.

When Google and Facebook embraced it back then, the community was small and fresh, so their adoption of XMPP was quite the boost.

When Google quit and took its users there was a significant user base that disappeared.

The fediverse exists for almost a decade and it has a stronger user base. Meta can try to extend ActivityPub and we can only hope the devs don’t cater to their needs above anyone else’s (maybe we can learn from Mastodon’s influence). When Meta tries to extinguish it’ll only take their users with it.

They can already fetch all the public data they want without federating.

I dislike preemptiveness but everyone would have to be on their toes to react to any ill intent (like trying to change ActivityPub although that’s not really a well-defined protocol to begin with).

I’m still on the fence but leaning towards block.