Hmm...this is new to me, but if Microsoft is going to stop supporting anything, it's just their own
implementation of OpenGL. I confess to being surprised they even had one, I for one have never been aware of anything other than the OpenGL support built into videocard drivers
from ATI and nVidia.
OpenGL itself is thriving and well evolved - AFAIK there is no reliance on any Microsoft-specific code for using it, be it in games or desktop applications.
If someone knows more about this, I'll be glad to stand corrected