Unless something drastic changed (or I'm utterly misinformed) you could run your own server - and you'd split the network. The explanation was, as far as I recall, that there's no easy way to route things if all you got is a mobile number as an identifier (So .. on what server is that client? A JID has a host, a mobile number doesn't).
To reiterate: You probably could run your own server. In which case you and the 3-5 people you might convince to use that server would share some infrastructure under your control. You would not be able to send a message to the 6th friend that happens to use TextSecure, but _also_ needs to be on the authentic/real network to chat with his family.
Edit: Partially based on https://twitter.com/moxie/status/438049169052155905
TextSecure certainly seems the best option, but its adoption wouldn't help me a lot (I could migrate my wife, my parents - but I most certainly won't be able to use it beyond that circle) and - I really, really dislike central services for communication. This isn't even a serious trust issue, I do believe that the developers of TextSecure are genuinely offering a great and secure text chat experience (ignoring that other solutions promise the same - Threema et al for example, but TextSecure comes with a lot more credibility and therefor trust). But I like to stay in control of my infrastructure. The xmpp server is the best fit - but the protocol and clients cause some issues and No One™ is using it, so the federation is a moot point.