I read this message this morning, and pondered this for quite some time. It's definitely not impossible, but there's a college thesis worth of conidiations and difficult problems to address. There's probably already a number of products that would be a better fit than federation.

The torrent system as it is, is ill fit, it's got the distribute things and protect them with hashes in spades, but unlike forums it doesn't need to deliver you data in a timely fashion. If that copy of Scooby Do and the Reluctant Werewolf takes a couple of days for someone to come online and have you a few k of content, it's no big deal. That said, it IS possible to watch really popular videos over BT.

I think the deepest problem is trying to keep the data online. You obvious can't have a multi-terabyte copy of forums on everyone's box, people are going to need to split and choose who gets what but they you have to figure out a way to keep everything everywhere online. You can't just force people to host everything or you'll end up with unexpected jailbait hosting.

You'd have to sit down for a long time and draw up a spec to even define what your problems are, you'd have to figure out things like, how much of the data do you expect to be available all the time, how many copies do you seed around, how you'd manage to keep people seeding it.

Policing and moderation also becomes a sore subject. Most of the P2P stuff is resilient against removing items by deisgn, it's immutable once launched. For things like edits, you could do versioning systems, but like if someone was doxxed or someone posted nudes of their ex, there's no way to remove the old versions.

Authentication and identification would be a nightmare. you'd probably need to digitally sign everything and keep your keys in a chain of custody, signing each new key with the old one.

it's an awesome thought exercise though.