Witcher 3 lead programmer Balazs Torok on DX12:
I think there is a lot of confusion around what and why DX12 will improve. Most games out there cant go 1080p because the additional load on the shading units would be too much. For all these games DX12 is not going to change anything. They might be able to push more triangles to the GPU but they are not going to be able to shade them, which defeats the purpose."