We announced our plans for add-on compatibility and the transition to WebExtensions in the Road to Firefox 57 blog post. However, we weren’t clear on what this meant for Firefox for Android.
We did this intentionally, since at the time the plan wasn’t clear to us either. WebExtensions APIs are landing on Android later than on desktop. Many of them either don’t apply or need additional work to be useful on mobile. It wasn’t clear if moving to WebExtensions-only on mobile would cause significant problems to our users.
The Plan for Android
After looking into the most critical add-ons for mobile and the implementation plan for WebExtensions, we have decided it’s best to have desktop and mobile share the same timeline. This means that mobile will be WebExtensions-only at the same time as desktop Firefox, in version 57. The milestones specified in the Road to Firefox 57 post now apply to all platforms.