I see the point.
I was thinking about using a small, simplified, reliable fixed set of
basic GPU functions which are always supported, and call them from time
to time to speed up some mass operations such as texture scaling
(instead of MMXing big textures on CPU, call existing OpenGL driver
Trying to combine two OpenGL implementations it's technically difficult.
Furthermore one might thing combining two implementations gives the best of
both, but easily gives the worst of both worlds, because there's overhead
moving data between them.
Image the worst case scenario: draw on
