Remember there are two areas of Metal, the next ten OpenGL and the GPGPU compute side which has taken over from OpenCL as the preferred compute API on OS X.
Mark gave good reasons why the 3D side of Metal may not be of interest to Izzy users I'd be very surprised if the compute side of Metal wasn't on the radar in the medium to long term. Imagine there not being a distinction between CPU and GPU nodes because everything is executed on the GPU.
Windows has a choice of Vulkan and DX10 which also feature 3D and GPGPU Compute in a similar way to Metal. I'm sure it's a lot of work ahead, even for a genius...