Making a messaging system that piggy backs on top of hidden services is (relatively) easy to do. There are already designs out there and as a matter of fact such a system is about 85% implemented already (alpha mixing + all mixes are hidden services + PIR network for message retrieval + decentralized directory servers + nymservers + automatic message encryption + dummy traffic + provably secure cryptographic packet format). The challenge is extending what is already done so that it can support multiple types of traffic, rather than just E-mail like messages. Currently I am thinking of how what is already done can be modified into something that can be used for things like surfing the clearnet with mixing, running traditional hidden services with mixing, being a file share, etc. A network that meets multiple use cases. One thing that I think would be nice is to add network wide plausible deniability, but that would entail making it a P2P network I believe (or H2H like I said). That doesn't mesh well with the (semi-centralized, definitely not P2P) private information retrieval system that has been implemented. I am trying to determine how hard it will be to modify the system so that it can encompass all of these things, without having to scrap large parts of the work that has already been done. Perhaps replacing the PIR part of the system with something like Freenet will be adequate. Perhaps the system should be left for messaging only.