""Over time, the list of content that Firefox can block will increase to the point where the browser will block all Flash content by default in 2017. That’s when Firefox will require “click-to-activate” approval from users for all Flash-based websites that not have switched to HTML.
In March 2017, Firefox will also completely drop support for all the NPAPI plugins, with the exception of Flash. The enterprise version of Firefox (ESR), which Mozilla will release the same month, will continue to support the Flash and Java plugins until 2018. Users who may still want to have Flash enabled by default could switch to Firefox ESR to use Flash for a while longer.
Flash has been the source of many critical browser exploits, so web security should improve significantly once major browsers do not support it anymore and most websites have made the transition to 100 percent HTML content.""
Honestly I'm surprised Flash has lasted this long, especially considering a huge percentage of traffic is Android and iPhone based, and they don't support Flash.