There's still a thriving (albeit small) community of skateboarders, retro enthusiasts, and even some AV pros who have FireWire equipment in active use.

In the kernel, the last commit in the IEEE 1394 area was a month or so ago—it's not 'active' maintenance, but its definitely being maintained, and is quite stable in my testing. (Thanks a ton to the current maintainer, who's going to go through the 3 year process of sunsetting full kernel support, and coordinating that with external projects!)