Apparently I missed this the first time around, but Adobe has decided to continue supporting the NPAPI version of Flash Player on Linux. They have just released their second update, Flash Player 24 Beta, on October 28th for both 32- and 64-bit platforms. Before September, Adobe was maintaining Flash Player 11.2 with security updates. Adobe has also extended NPAPI support beyond 2017, which was supposed to be the original cut-off for that plug-in architecture on Linux, and pledge to keep “major version numbers in sync”.
This took me by surprise. Browser vendors, even Mozilla, have been deprecating NPAPI for a while. Plug-ins are unruly from a security and performance standpoint, and they would much rather promote the Web standards that they work so hard to implement, rather than being a window frame around someone else's proprietary platform.
So what are Adobe thinking? Well, they claim that this “is primarily a security initiative”. As such, it would make sense that, possibly, and again I'm an outsider musing here, the gap between now and 11.2 was large enough that it would be easier to just maintain two branches.
Whatever the reason, Flash on Linux is continuing to be supported for all browsers. If you find yourself at the intersection of Linux, Firefox, and hobbyist-developed Tower Defense games, you can pick up the latest plug-in at Adobe Labs.