Re: the hosting of topics/subreddits in the DHT, I've done quite a lot of research [1] into a very innovative yet not well known P2P publish-subscribe network design [2] from some Norweigan computer scientists that removes the role of hosting for nodes not interested in a topic, even designing a decentralised microblogging platform on top of it [3].
It's called PolderCast, and the way it works is that it models subscribers of a topic as a ring, and then uses 3 different overlay networking modules to efficiently constructing the network (a basic gossip one, one that finds nodes with intersecting interests, and then a final one which constructs the neighbours for a node in the topic ring). Thus, only subscribers of a topic are responsible for hosting, in contrast to a DHT where every node would be (even for questionable content that they may not agree with).
I have an idea for a federated blockchain to support a subjective crypto currency. So each coin's value is unique and determined by whoever might be trading it. The way that knowledge of the network state will flow looks like boosted gossip, maybe similar to PolderCast layers.
It's called PolderCast, and the way it works is that it models subscribers of a topic as a ring, and then uses 3 different overlay networking modules to efficiently constructing the network (a basic gossip one, one that finds nodes with intersecting interests, and then a final one which constructs the neighbours for a node in the topic ring). Thus, only subscribers of a topic are responsible for hosting, in contrast to a DHT where every node would be (even for questionable content that they may not agree with).
[1] http://liamz.co/wp-content/uploads/2015/03/Computer-Science-...
[2] http://acropolis.cs.vu.nl/~spyros/www/papers/PolderCast.pdf
[3] BitWeav http://liamz.co/wp-content/uploads/2015/03/whitepaper.pdf