There was a time when browsers needed a little help to deliver decent multimedia content, but we're fast leaving those days behind. For proof, look no further to Google and now Mozilla's decision to cut the ancient Netscape Plugin Application Programming Interface (NPAPI), the core API that allows plugins such as Flash and Silverlight to operate.
While Google has already disabled NPAPI support in Chrome, Mozilla has only just announced that by the end of 2016, it'll be gone from Firefox too:
Firefox began this process several years ago with manual plugin activation, allowing users to activate plugins only when they were necessary. This decision mirrors actions by other modern browsers, such as Google Chrome and Microsoft Edge, which have already removed support for legacy plugins.
It goes without saying, but if you're looking to invest time in any that relies on NPAPI technology, don't bother. For game developers, this includes Unity's web player, with the only option going forward being the middleware's flaky WebGL export option. Not that Mozilla is leaving Unity out in the cold entirely:
As part of our plugin strategy, Mozilla and Unity are proud to jointly announce a close collaboration and an aligned roadmap that will enable Unity-based content to be experienced directly in the browser without plugins. As this technology continues to evolve, Unity has announced an updated roadmap for its Web Player technology.
Flash will also get a stay of execution, simply due to its prevalence:
Because Adobe Flash is still a common part of the Web experience for most users, we will continue to support Flash within Firefox as an exception to the general plugin policy. Mozilla and Adobe will continue to collaborate to bring improvements to the Flash experience on Firefox, including on stability and performance, features and security architecture.
Mozilla announces the end of NPAPI plugins in Firefox [Mozilla, via gHacks]