Update: AMD has provided an official statement to us clarifying the matter.
“There have been reports based on a video of Richard Huddy of AMD making speculative comments around DirectX 12 support on versions of Windows. Richard Huddy does not speak for Microsoft, and he was unfortunately speculating from Microsoft’s publication of key dates and milestones for Windows 7 lifecycle and mainstream support policy. Richard has no special insight into Microsoft’s Windows or DirectX roadmaps. Microsoft is a key, strategic partner for AMD and we’re continuously collaborating with them on DirectX 12.”
AMD has seemingly given us the first details on which operating systems DirectX 12 will be compatible with, or rather, the OS it won't work on.
At a recent PDXLAN event, the company's chief gaming scientist, Richard Huddy spoke about Windows 7, commenting "One thing that's not going to happen to it is DX12, yup, DX12 is not coming to Windows 7."
Microsoft has stated that DirectX 12 can double the framerate and cut power consumption requirements of systems using it by half. The feature will ship with Windows 10, which is set for release next year, and will also be compatible with Windows 8 and Windows 8.1, as well as Xbox One.
To watch Huddy's comments on DX12 for Windows 7, skip ahead to the 20:50 mark in the below video.