On March 20, 2014 at 10AM, DirectX 12 will be revealed at GDC. There really isn't much to go on right now outside of a very green DirectX 12 landing page on the MSDN website.

Interestingly, the notable logos on the page show the usual suspects of AMD, Nvidia, and even Intel. The real interesting one is Qualcomm Snapdragon, meaning that DirectX 12 might have a big focus on future mobile devices.

It will be interesting to see if DirectX 12 requires all new hardware and/or a whole new operating system (Windows 9) just to be used.