The only thing I'm worried about is that this stuff has been there all this time. Yet no one knew about it or was aware of how to use it? Now its out there, will it actually be used and matter at all?
1) Almost nobody is writing high-end games for OSX or Linux.
2) None of these features are supported on mobiles (which use OpenGL ES).
3) Consoles don't actually use OpenGL, they have their own APIs. The PS3 supports OpenGL and OpenGL ES, but it's only there for lazy porting and isn't as fast as Sony's own API.
4) Console's don't have much of "driver overhead" and developers have been able to batch stuff in ways PCs only dreamed of for over a decade.
5) You're guaranteed to get more compatibility problems by releasing an OpenGL game on Windows than a DirectX one. Microsoft doesn't provides OpenGL support in their default drivers, but they'll run DirectX 10 and 11 games out of the box. For OpenGL you must go to the vendor website and install a proper driver.
6) Since these features were barely touched, you're almost guaranteed to find lots of bugs and glitches when trying to use them (like most of the high-end rearely-used OpenGL features), specially on non-NVidia hardware and on Apple's shoddy OSX OpenGL drivers.
OpenGL's "zero driver" isn't correct: OpenGL defines only an API and all implementations (including the goddamn shader compiler) is the GPU vendor responsibility. This means some vendors can interpret things differently, specially in details that weren't specified in the documentation (this often includes error reporting, how to deal with invalid data, etc).