Hmm lets see, "linux" is not ready for games so don't make any games. Because no one makes any games, there is no need to address what a game needs...
Thats not how things move. Linux officially is ALSA, and that must be your main concern. Few people will bother with OSS nowdays. Also, SDL can abstract you from that, and ease pulseaudio/etc in the process.
So what you need is OpenGL, SDL (and OpenAL) and be done. Don't bother with low latency at this point, or support jackd if you are that picky.
Drivers? We all know ATI drivers suck, and until AMD gets their act together, they will still lose linux customers. Of course, since "no one" play games in linux, that shouldn't be a concern would it?
They won't move until they see a growing community, and its possible right now with nvidia, using just opengl and sdl. Such a community will become apparent when things like source/steam in linux become a reality.
So what if steam/source becomes Nvidia only on linux? If thats what it takes to make the likes of AMD to act, so be it. There is no reason why AMD can't provide decent drivers the way Nvidia does, and its their sole fault since they won't release specs.