I've been mulling over the idea of a vouch-based social network. You can follow someone or whatever, and you can also tag them as "person I've met" or "my uncle." If you see a post that's insane or spam, you can open a little graph that shows you that the reason you're seeing this post is because this is your friend's friend's friend, and you can bug your friend about it. Everyone will have a responsibility to only tag people who they know are actual real people who post content with their hands.

A next generation spam filter, perhaps. Rather than answer your interesting emails, the communication tool that leans into LLMs will show it to you so you can respond to it personally or have the LLM make a response that you review. And as for it being a different protocol, it would handle a lot more messages through training rules about which messages to filter, which to store long term, which to store short term, etc.