Starting next year, Firefox users who navigate to pages that contain Flash will be asked for their consent before activating the plugin. The move, long expected, comes as developers seek to curb usage of Flash in everyday web browsing. The browser will also begin blocking non-essential Flash content next month, as another step to making the browser run more efficiently. Mozilla previously announced plans to remove support for NPAPI plugins by the end of 2016 but it appears the company has opted to push the deadline back to March 2017.
Source: https://threatpost.com/firefox-to-block-flash-in-august-disable-in-2017/119419/