Patchwork is the easiest way to get an overview. They still have a manual invite method that gets you into a pub server but it is pretty easy and well documented. I think it would be more reliable long term to have a EOS token you could stake instead to incentivize pub servers to keep encrypted user data for them under predictable terms. I could see user's electing their favorite pub server providers.

Because you have an incentive system then it should be reasonable to scale it to handle larger storage and network bandwidth. There is a need to have sharable semi-private high-value media like: videos, scientific documents, books, and of course chat, etc..

The protocol would need to be changed or augmented to be light-client friendly. I think this can be done by adding a on-going state that summarizes the log where each session updates the state and removes the need to parse prior log entries. Much like EOS does except state is on disk not ram and would not have as much of a size constraint.

Anyway, it really is very simple in its present form and it is a good starting point. In any event, I found it a good learning experience. It is an example we can look that naturally gives each user their own chain ("log") so they don't all have to be on the same chain and will be easier to run it off-line after sign-up or in rural areas. This helps circumvent the ISP problem ..