Well, it makes me sad that we would have to, but that doesn’t make me agree less that it would be necessary to keep a real alternative in existence.
Every instance that allows Meta should not be considered part of the Fediverse anymore, but is now Metaverse. Mastodon/Pleroma/Lemmy/… will then just become the running software, but not by default ‘Fediverse’ anymore, that choice will become the admin’s: Fedi or Meta.
In a perfect world we can still keep the big parties out for those that choose to, though at first it will be hard, not only to keep up with instances leaking both ways, but also hard to let go of the unrelated users that had no choice in the matter and are now presented with: change server or follow the server’s choice, and the second choice will be the least trouble for most. In other words: many followers will be lost and many currently followed won’t be reachable anymore.
I personally am on the side of keeping the Fediverse separate from the Metaverse, I’d even concider the defederation of any leaking instance just to avoid the possible connection. Hence, I already went ahead blocking the Threads domain and will do my best to keep Meta out…
That being said, as I was reading one of the longer comments, I did contradictively think of a counter-point too… As was said, the current way of Federation only federates followed items and it has proven to be rather tedious if you want to see posts from an account from before it got Federated (my client now has a 'Load from remote instace" button that kinda solves this seemingly local (in the app), but even there it’s an extra click per profile to a second profile window just to see what I would expect to already be on the first). This is kinda annoying when scouting accounts to follow, as many will have (ex.) 2184 posts, yet after scrolling 7 it says there’s no more. On top it also makes the ability to encounter something or someone interesting to follow (unless somebody locally already follows them) kind of impossible…
Relays are a crooked band-aid solution to this, but are instance-targetted and you’ll have to add any you encounter one by one if you’d want your instance to work like Twitter and Reddit where content can find you (and with constant access to all (or most) content), while filling instances storages exponentially. So relays are more like ducttape than a real viable long-term solution to this.
In comes a big company instance that, if our instances would be busses and trains, has a comparable size of a planet, which technically could be exploited to relay stuff while leaving the attached media linked from their copy, and as a global index. Every account could be connected to any instance without having to store the entirety of it; any content creator could be fully seen at any point in time from any instance (if they wanted to); it would make federation a lot less intensive as it’ll just have to query the giant (if adapted for this use),…
But is that worth giving up my privacy to them again? Is that worth bowing to them as they assume authority over me again (like the power to cut me off from, not only the Metaverse then, but even the whole Fediverse too, should they (wrongly) suspect or misjudge something someone says? (A thing that will be bound to happen eventually, cause social media is probably the easiest place to get misunderstood, misquoted, oversimplified,… and getting a bunch of predispositioned opinions against you…)) And with Meta there isn’t even anyone to explain yourself to or complain to, which makes all that even worse…
So, my answer still remains No on direct interaction,… I’m not yet sure on my position on defederating ActivityPub instances that federate with Meta yet though… I’ll still need some research and input for that before I’ll decide for sure.