Unfortunately Mozilla seems too afraid of giving up control. As far as I know, up to the point Persona went away the official deployment instructions were still

Unfortunately Mozilla seems too afraid of giving up control. As far as I know, up to the point Persona went away the official deployment instructions were still "don't host your own copy, use Mozilla's, because it might change", effectively making the thing moot (still centralized). And for password management, bug 1344788 is still open so it's not possible for password managers to integrate with Firefox properly, and they have to do hacks that involve running scripts on the untrusted page instead…