Glad to hear you think Subchains are interesting!  There are several of us that hope to continue developing them through Unlimited and Classic, in cooperation with some of the bigger miners.


Do you mean what am I writing code for?  I haven't written much Bitcoin-related code since working on Sigsafe [video, paper, dev] last year.  

If instead you mean what am I working on, well one of the things I'm working on is to make "Unlimited" the preferred client for users and "Classic" the preferred client for miners.  I see these two implementations as not only complementary, but symbiotic.  I'm working on getting the first 1.1 MB block mined into the Blockchain and decentralizing development away from Core.  

You do bring up a good point with the semantics behind the word "developer" though.  Due to perhaps some historical accident, there is a lot of emphasis placed on "writing code" in the Bitcoin community and less emphasis on scientific research and engineering development (and even less emphasis on the social sciences).  As Bitcoin matures in industry and academia, I wonder if we'll adopt labels such as "researcher", "engineer," "programmer," "scholar," etc.

One of my goals with Ledger was to build an academic and interdisciplinary communication channel that would allow bright minds in economics, sociology, physics, law and political science to contribute at the highest-level towards the evolution of Bitcoin--something previously dominated by those writing the code.  One of the ideas I'm working on is the "five sectors of cryptocurrency knowledge" shown below:



I like this diagram because "consensus and mining" is right in the middle where (IMO) it belongs.  Bitcoin achieves consensus not for technical reasons alone, but because of the interaction between technology and the people running that technology.

The "Bitcoin System" boundary encloses not only the node software and mining hardware--it encloses each and every one of us too.