In the upcoming version of DF, will you upgrade to the much improved yet backwards-incompatible SDL v2.0, or stick to what ain't broken? I seem to recall that SDL support was implemented by another person, so you might not be the right person to ask.
And, to what extent is DF hardware accelerated? Do physics simulations, such as water flowing down a river, take any benefits from GPGPU? I would imagine the parallelization that comes with it would be beneficial, but I don't know if the flow of water relies on ticks in the main loop or what. If nothing like this is implemented right now, do you think utilizing GPU Compute would be viable? Would it be something you'd even consider doing yourself, this project being a one-man-band and such?
Toady has said before that he doesn't really understand the SDL code, and the collaboration was a bad experience. On that basis the upgrade is not planned for any time soon, unfortunately.
DF is almost entirely single-threaded (with minor exceptions), and there are no plans for multi-threading support in the foreseeable future. There's an old joke: I had a problem, so I decided to use multithreading -
I/four/Now/problems/have...
Basically, things which require painful rewrites are deferred in favor of adding (simulation) features - remember that DF is only about a third of the way towards a complete alpha version!