I think if it comes to it, Microsoft will invent WebDirectX under the guise it's for Windows 8 metro apps, and simply left it on in IE10. 3D on the web is a niche so it doesn't make their browser uncompetitive. Besides, they can also claim "you can do the same thing in WebDirectX anyway, just use that" - and they don't have to be seen supporting OpenGL (who cares if anyone writes wrappers? they don't have to pretend WebGL is a good idea).
For the record, it's an utterly backward and damaging thing to do to the web, but they'll do it anyway.
