Flash browser plugin on Linux to be limited to Chrome
Quoting “Adobe and Google Partnering for Flash Player on Linux” by Mike Chambers for the Adobe AIR and Adobe Flash Player Team Blog:
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.
It’s probably a combination of two factors: First, Adobe may be starting to invest less in Flash (as witnessed by the discontinuation of mobile Flash). Second, they may think that browsers other than Chrome are not important enough on Linux, any more.