Recently I've found out that Chrome and Firefox are dropping NPAPI plugins support by January 2013. Anyway, reading the blog messages with more attention, it seems that NPAPI plugins will be just disabled by default and not actually impossible to use.
What will happen? Will I be able to use my NPAPI plugin in Chrome/Firefox after January 2013? It's pretty complex enterprise plugin, so we would like to avoid reimplementing it.
Starting in January 2014, Chrome will block webpage-instantiated NPAPI plug-ins by default on the Stable channel.
To give people more control over their browser, Firefox will no longer activate most plugins by default.
I've also found another post on Firefox Dev's Blog, saying that I can try new plugin management system in Firefox Nightly. It was enough to set "Always Activate" to make the plugin work. Will this remain this way?
The phrases "block by default" and "no longer active by default" are referring to things that look, in general, like the last post you linked to. Neither will make it impossible for users to use NPAPI plugins. They will require users to explicitly approve instantiation of NPAPI plugins.
However, the Chromium blog post also says: "Eventually, however, NPAPI support will be completely removed from Chrome." When that happens, it will be impossible to load NPAPI plugins in Chrome.
来源：https://stackoverflow.com/questions/19457786/npapi-support-in-firefox-and-chrome-actually-dropped