Timeline for deprecating everything that isn&#x27;t using the new WebExtensions API is 12 to 18 months:<p><a href="https:&#x2F;&#x2F;blog.mozilla.org&#x2F;addons&#x2F;2015&#x2F;08&#x2F;21&#x2F;the-future-of-developing-firefox-add-ons&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blog.mozilla.org&#x2F;addons&#x2F;2015&#x2F;08&#x2F;21&#x2F;the-future-of-dev...</a>