I want to see a hybrid federation/p2p approach (Secure Scuttlebutt pubs/rooms are close this). As far as I understand it ActivityPub is just a standard for interop between social network services. The social networks still own your data and while they do offer tools for migrating between them you are still essentially at their mercy. You could run your own instance but you'll run into the same problems as you would running your own email server. Not every one will have to ability to do that and you could still run into the 'gmail problem' where large instances refuse to federate with small user instances.

It would be cool if there was a protocol that was fundamentally p2p but with a federated 'tracker' layer that is basically indistinguishable from normal social media sites to casual users. The social media sites would help propagate the content and if one went down or refuses to track your content you can just peer with another one (or just continue to share content with your personal network of followers over a gossip protocol like SSB without the need for a tracker)