Microsoft only controls the software development.  Sure, the last several generations of GPUs have been developed in response to or in parallel with the DirectX roadmap.  That said, once those features are established and implemented, they can always be supported through updates to OpenGL.

Here's a quote from a recent news article posted on www.opengl.org:

“DirectX 10 hasn’t lived up to any of its promises, and in fact has been a titanic disappointment. More than that, the features that are supposed to be unique to DirectX 10 can also be exposed in OpenGL. Given how few people readily jumped on the Vista bandwagon, it’s safe to suggest there might be a slight paradigm shift to favoring OpenGL, especially now that DirectX has had its components largely broken up.

A rejuvenated interest in Mac gaming more than likely means rejuvenated interest in OpenGL, which is NOT platform dependent as DirectX 10 is. A rejuvenated interest in OpenGL means the potential for DX10 features outside of Windows XP. In short, DX10 is, at least at the moment, bust, and the features it boasts so proudly may indeed wind up making the journey back to Windows XP in the form of updates to OpenGL.”