Personally, I think its great to think about protocols and the tech that goes into it... but only because its interesting to me technically.

Some of this kind of sounds like: I have a cool protocol and now Im in search of a problem that I can apply it to. What app should I duplicate first?

You need to flip this around and ask: what kind of service can I build that would deliver new or additional value to users, that is a significant enough improvement that users will switch en mass.

Then go do that, get a bunch of users, and then release your protocol and encourage others to participate.

There's nothing wrong with doing it all in parallel, but the primary problem -- getting users -- is large enough to consume all of your energy.