Right now, Adobe provides a stand-alone version of the Flash Player Linux users can install. However, in cooperation with Google, Adobe has been working on moving the Flash Player to the Pepper API, a modified version of the NPAPI currently in use. Chrome already supports Pepper, but Mozilla has no plans to do so, and as far as I can tell, neither does Opera (if someone can correct me on Opera, please do so). The non-Pepper Linux version of the Flash Player will be discontinued.
"For Flash Player releases after 11.2, the Flash Player browser plugin for Linux will only be available via the 'Pepper' API as part of the Google Chrome browser distribution and will no longer be available as a direct download from Adobe," Adobe's Mike Chambers writes, "Adobe will continue to provide security updates to non-Pepper distributions of Flash Player 11.2 on Linux for five years from its release."
Flash Player for Windows and Mac OS X is not affected, since non-Pepper versions will still remain available for those two.
This is all part of Adobe's effort to move away from the Flash Player. The mobile versions had already been discontinued, and step by step, the other versions will be discontinued or de-emphasized as well. With the arrival of HTML5 and Adobe's inability to deliver acceptable performance on platforms other than Windows, Flash Player's fate was sealed.
All the more reason to move to WebM HTML5 video.