This is what I don't get about the anti-Meta paranoia. Their worst case scenario is... exactly the same as we have now. They can't make every single instance hand them over their whole userbases, that's not how federation works.
I get why they don't like Meta, but I have friends who use Facebook and Instagram, and maybe it would be nice if they could get a taste of the Fediverse experience. We might end up gaining more than Meta.
How would they even extinguish a whole ecosystem of independent instances? What does that even look like?
They could very well make some feature or requirement and demand that every single ActivityPub instance uses their version to remain compatible...
...and instance hosts can just say no, fork it and keep going unbothered.
Even buying up some big Lemmies and Mastodons is not going to get them the whole Fediverse.