Hi lifeisstillgood, I am one of the core Persona developers. Persona is a pretty awesome project with very ambitious goals. We obviously want to see growth explode and are working hard to make Persona great for both users and site operators.
Persona's growth has been steady, primarily driven by newly developed sites. We hope that as the user base grows and support for the BrowserID protocol is natively built into the browsers, existing sites will have more of an impetus to offer support.
A version of Persona is already integrated into FirefoxOS and we hope to offer support in desktop Firefox by the end of the year.
If you want to participate in discussions, have an idea on how we can improve, or just want to see what we are up to, our mailing list is open to everyone: https://groups.google.com/forum/#!forum/mozilla.dev.identity