At least with all d3dx10 DLLs released so far, D3D10_SDK_VERSION has not changed. Obviously, if it does change in the future, we will need to accommodate that in new DLLs.
Although I suppose we could hard-code the SDK version into the DLLs now, rather than having to change it later, which I guess is what you were getting at, Henri. I'm not too convinced Microsoft is likely to change it during the D3D10 lifecycle, but I guess it doesn't hurt to be safe.
Cheers,