When Mozilla launched Persona under the name BrowserID back in 2012, it had big plans for the authentication service. The primary goal was to make the authentication process on the web safer, more private, and better to use.
BrowserID was renamed to Persona in the beginning of 2013, which resulted in Personas, the lightweight theme engine of Firefox, being renamed as well to avoid confusion.
Persona has been available for more than a year in a stable version, and it appears that it has not gained the traction yet that Mozilla hoped it would get. Reasons listed are that Mozilla failed to leverage the Firefox user base, that large sites like had enough resources to create and maintain their own authentication system, and that the services feature set is too complex.
The organization today announced that it transitions Persona to community ownership. If you are a user of the Thunderbird email client, you know what that means: Mozilla pulls employees from the project to assign them to different projects and tasks, while "entrusting Persona's ongoing development to its community".
That does not mean end of support though, as Mozilla staff will still be responsible to fix critical bugs, security issues and service interruptions. But when it comes to new feature additions, or improvements beyond maintaining the status quo, it is solely the community's responsibility to deliver those.
Mozilla will continue to host Persona and make use of it on its various web properties for the time being. What this means is that Mozilla will not decommission Persona in 2014 as the FAQ notes.
Nothing changes for websites and services that make use of Persona. The authentication system continues to work and no changes need to be made.
While it may not be possible to compare the Thunderbird situation with Persona right away, it is likely that Persona will face the same fate as the email client, meaning that updates will concentrate mostly on fixes and existing issues, and not on feature additions.
The resources that are freed by the transition are assigned to the development of the Firefox account system that works across devices and is responsible for features such as Firefox Sync, the marketplace, or the find my device feature.
Persona's future looks bleak, especially if you look at Thunderbird's transition to a community project. Yes, it will still be maintained and works just fine, but since it has not reached the adoption levels when Mozilla put resources behind the project, it is very likely that adoption will slow down even further or even come to a halt due to the change.