I don’t think this is nearly as difficult as you are implying. All it would take is for a social network to require some kind of verified ID that is renewed on a regular basis. You might even need to verify this ID in person, physically. This might seem excessive today, but if the internet becomes unusable due to excessive AI content, it’s not that big of a deal. The infrastructure is practically already here via banking and government apps.
The alternative is that everyone just accepts the internet as a place where you can’t tell if anyone is real. I don’t think that will be a happy state of affairs for anyone.
Even if this isn’t a “required” thing, it will become a desired one by consumers. Who would you rather follow - the verified Taylor Swift account, or the unverified one? Non-verified creators will be relegated to niches where it doesn’t matter as much if they’re real or not.
Then you might say - but a person can just use AI tools and paste them into their verified account. Which is fine - I’m not saying that people aren’t going to use these tools to create content. I’m saying that these tools aren’t going to eliminate the possibility of an individual person creating content on the Internet as a human being, and being verified as such.