Open-source would at least make emulation a hell of a lot easier...on the other hand, we wouldn't need to emulate in the first place because people would just make source ports of whatever they want that will properly utilize the latest hardware.
I mean, if ASP/CSP and EMU8000 emulation were supported in DOSBox so that TFX and Eradicator respectively could sound their very best, there goes any incentive for me to deal with real AWE32 cards. Then there are all those Aureal A3D games from the Win9x generation that wrappers like ALchemy are useless for, since it turns out that A3D is its own API separate from DirectSound3D, and Creative now has it buried and unused after buying out the bankrupted remains of Aureal...
Speaking of which, if someone could make an OpenAL renderer that also had DirectSound3D wrapping, binaural HRTF mixing for headphone usage, and supported EAX 5 for those games that use it instead of the vendor-independent EFX reverb/chorus/occlusion effects, then I could do without Creative sound cards altogether! But of course, they won't let that happen if they can help it...