I do have a concern which I addressed in the Wine Users mailing list:
Wine is not only used with Linux, it is also used with other *nix implementations, to include the one that use, MacOSX. Will there be a port to this platform or some sort of 'hook' that will allow the use of your drivers on this platform.
If you want to use the Gallium D3D10/11 implementation on Mac OS X, you will need a Gallium driver that can run on Mac OS X.
The software renderers probably already work.
For hardware acceleration, my proposal is to write a new Gallium driver that uses OpenGL underneath and can thus run on any platform providing OpenGL.
I think that implementing such a Gallium driver is easier than implementing D3D10/11 from scratch, and will also benefit Mesa, since it will be possible to test additions to the Gallium interface without needing to write hardware-specific code or writing software rasterization code.
I'm not sure if I'll write such a Gallium driver myself. Contributions would be greatly welcome. It's a fun project and certainly much easier than writing an actual hardware driver.
Alternatively, you could port the kernel DRM and drivers to Mac OS X and other systems, but that's much harder and much less user friendly.
At any rate, nothing stops Wine from also implementing D3D10/11 using WineD3D or OpenGL, and using that if a Gallium driver is not available. Note however that D3D10/11 are totally different from D3D9, so I'm not sure how much you can share (especially if you want a fast implementation, which may be impossible anyway over OpenGL).