In my opinion, nothing. If Meta is able to effectively take over Fediverse as people are claiming, then the Fediverse was never destined to survive to begin with. On to the next thing. This is the first real test of the resilience of this type of “decentralized social network”, and if it ends up going to shit, it would have eventually anyway.
The extra step is that it doesn’t run through Safari.
What I’m saying is that if there’s always this constant corporate threat, if there’s the functional possibility of it happening, then it will eventually happen. If not Meta, then Musk, or god forbid Trump. Having to constantly “defend” against a mega instance does not seem like a sustainable future for the platform. That said I don’t think this is even an issue. There will always be instances that fundamentally don’t and won’t federate with Threads and other potential big players, so just go there. That’s kinda the point of this whole thing isn’t it? Activitypub and Lemmy/Mastodon won’t go away just because most people are somewhere else.
WefWef UI is great, just wish it wasn’t a web app