I've done a bit of research and the last update on their GitHub page for the changelog was way back in 2012 when Cycling 74 was still in charge. I guess I should consider myself lucky that it still works on Yosemite. The original creator, Cycling74 sent it off to Rogue Amoeba, which has a handful of very useful apps. They now offer Soundflower as a freebee. On their software status page every other current app has been updated to support El Capitan. It looks like they've rolled soundflower development into their yet to be released app Loopback which will be sold instead of given away. Back in early August they offered beta testing slots, but those are all full now. This might seem like a relatively obscure piece of software, but it's been invaluable to many professionals that need to manage separate audio sources as one and output their sound into recording tools, among other things. I personally use it often to share sound from my system and microphone, at the same time, with others on tools like Skype and Google Hangouts. Others use it to professionally record tutorials or create content for YouTube. As an example of one professional use, one person I've seen surprised by the lack of support was a professional that creates tutorials for the deaf, tutorials to help people learn to navigate the latest versions of OS X. I think this is the first time I won't be able to update due to a vital software component not being updated, unfortunately. I really hope Rogue Amoeba gets a stable version of Loopback on the market soon, because I will happily pay.