if we’ll have to retreat into a whitelist federation model with invite-only instances

That does not sound bad.

I wonder, what will happen to mainstream platforms.

If you talk to "regular" people without our background, they often enough don't believe that even astroturfing exists, especially not on "their" platform. So there will inevitably be a large amount of people who are oblivious to the fact, that they're talking to machines and feel like this is the real world. That's scary.

We're not ready because we're using concepts like "raising" to describe the creation of a probabilistic word sequence generator.

Don't anthropomorphize the algorithm.

AI is trying to model human text, so of course it is capable of degeneracy. It's never going to change so I don't think that's a useful measurement of when we are ready.