With the increasing use of open standards like HTML5, WebGL and WebAssembly, Adobe have recognised that many of the capabilities and functionalities that was provided by the Flash plugin are now being overtakenby these alternatives. As a result, they have announced the "end of life" for the Flash plugin.
Adobe will stop updating and distributing the Flash Player at the end of 2020 and are encouraging content creators to migrate any existing Flash content to these new open formats.
Roadmaps for browser developments are being updated, with Mozilla announcing significant restrictions to the use of Flash from 2019.
You can read the full Adobe announcement here.