Plugin Roadmap for Firefox
developer.mozilla.org
developer.mozilla.org
At some point in 2018 I decided to disable the Flash plugin on my system. I figured I would end up activating it maybe once every three months. I was surprised to discover that a surprising amount of video content is still displayed via flash players. Let's hope that 2019 is the last year of that crap.
Just stick to non-sucking sites and eventually other sites will go away or improve.
So much for giving the user freedom!