bittorrent sync is actually very much like this. People can offer read only subscriptions to their repositories, and then everyone distributes that repository to everyone else bittorrent style. So you have multiple read-writers who can publish and update the repository and multiple readers who can just subscribe to it and help to distribute.

So an example where this technology could be put to a unique use: Minecraft streamers and lets players sometimes like to distribute the world they are using. So they could make a repository of their world and distribute the read only keys for it to other users. This would allow them to play it, even temporarily make changes because sync kicks in and refreshes it, and the repository would be kept current as the world progresses. That should be viable right now with Sync.

Problem is, I think the bittorrent foundation is doing their damnedest to keep themselves firmly planted in the distribution and ownership of the technology. So we won't see an explosion of third party clients. I don't think it will see much adoption for this reason, and that's a real shame, because it would be a wonderful bit of kit for the internet.