I remember thinking about a similar concept a few years back. It would be good to have a p2p archive of human knowledge for end of the world scenarios. The problem is Bittorrent isn't the protocol for it, it doesn't allow incremental changes. You also don't want the complete history like git, you want something that passes a diff around. It would be great to have a p2p network with Wikipedia, a load of academic paper…
I worry, though, that this space is fracturing in a way that's hampering adoption. Between Freenet, Zeronet, IFPS, I2P, not to mention things like Retroshare, Matrix, and so forth, there's a lot of redundancy but with important differences between any given two solutions. I'm not sure what can be done about it, but it seems like something in this area needs a network effect to accelerate adoption, but to do that, it needs to be comprehensive in what it offers while also being sufficiently differentiable from other projects. It's great to see so much going on in this area, but it's getting difficult to know what does what, and where one might put some resources.