"Today we are announcing some major upcoming changes to Firefox add-ons. Our add-on ecosystem has evolved through incremental, organic growth over the years, but there are some modernizations to Firefox that require some foundational changes to support:
Taking advantage of new technologies like Electrolysis and Servo
Protecting users from spyware and adware
Shortening the time it takes to review add-ons
..."
Sounds like a bed of roses


