The slow bandaid-pull starts in September with Chrome 53. Google’s reasoning for the switch is Flash is — well, Flash:
Today, more than 90% of the Flash on the web loads behind the scenes to support things like page analytics. This kind of Flash slows you down, and starting this September, Chrome 53 will begin to block it. HTML5 is much lighter and faster, and publishers are switching over to speed up page loading and save you more battery life. You’ll see an improvement in responsiveness and efficiency for many sites.
The slow murder of Flash won’t take long, though. By the time Chrome 55 hits in December, Google plans to have HTML5 as the only option for Chrome users — unless a site only supports Flash.
If you visit a Flash site, Google will prompt you to turn it on for that page. HTML5 will always be the default.
Flash was good for its time, but it’s 2016 — good riddance to it.