Looks like Khronos finally got their API redesign, pretty good timing too.
But in order for this to take off there needs to be good drivers. Not sure if Apple will keep up-to-date drivers (past bad OpenGL support, Metal) and not sure how Microsoft will cooperate (DX12 still not available). So it's mostly up to the GPU manufacturers (NV, AMD, Intel, PowerVR) to maintain good drivers. From , it looks like there's still a lot of work to be done.
 - www.youtube.com/watch?v=KdnRI0nquKc
That video was a prototype driver from a year ago, the spec wasn't even complete back then.
For comparison, this one was still from 6 months ago, but as a side by side comparison with gles3, I think you'll agree that the driver isn't as bad as you suggested
I think Khronos have done a pretty good job of ensuring the spec came out at the same time as conformant drivers, and yes they wont be perfect and they will improve in time, but that will quickly ramp up with the amount of content that is out in the wild.