Email addresses and site-specific passwords already work just fine as a decentralized identity service. You can run your own email server(s) on your own domain(s), if you feel it necessary. Then again, you can use some other provider. Either way, basically everybody online already has at least one email account, if not several. Anyone who wants an email address, or even another one, can easily get one. Persona is trying to solve a problem that just doesn't exist, so it's no wonder we see so little adoption of it.
With FirefoxOS, Mozilla is skating to where the puck was in 2008. Android and iOS, among many others, just got there far earlier. FirefoxOS's HTML5/JavaScript/CSS approach looks much less appealing when it's also available on every other major platform, in addition to native approaches that these other platforms offer when performance or special functionality is needed.
If only we could harness cynicism to power our cities!
There isn't room for a third platform. Android and iOS can force developers to use Java or Objective-C through sheer numbers, but no other platform has that sway. If you look at the market today, every single player is pushing to make HTML5 a first-class target for application development: Microsoft, Google, Mozilla, RIM, Canonical, etc. Apple's original plan for the iPhone was only Web apps.
The Web, in all of its glorious kludgyness, is going to win on mobile the same way it did on the desktop. Firefox OS is just one small part of that overwhelming trend.
About Firefox OS, I was talking about the ubiquity of smartphones and similar mobile devices on a global scale, not just the existence of modern mobile operating systems. I don't think the former has peaked yet, and the Firefox OS team is hoping to make an impact in the developing world in particular. Regarding HTML5+JS versus native, in Firefox OS, HTML5+JS is native as far as applications are concerned, and Mozilla is providing and trying to standardize APIs for all of the "special functionality" that developers can only use through proprietary APIs on the other platforms.
With FirefoxOS, Mozilla is skating to where the puck was in 2008. Android and iOS, among many others, just got there far earlier. FirefoxOS's HTML5/JavaScript/CSS approach looks much less appealing when it's also available on every other major platform, in addition to native approaches that these other platforms offer when performance or special functionality is needed.