I think Grey likes to become a little too sensationalist and radical when it comes to things like this. The think we must keep in mind is that, while this is highly possible and even likely, it is certainly not certain. Just because it is possible doesn't mean people will let it happen. I'm not commenting on if that's a good thing or a bad thing, but in order for such a large scale replacement of humans to take place, people have to set it into motion, and other people need to allow it to happen, and there WILL be people who will fight this strongly. And if there are enough of them, they WILL win.
Furthermore, many scientists have agreed that recreating consciousness is largely impossible, and certainly won't happen soon. The human brain IS the most complex thing in the universe, and Grey doesn't give people enough credit for what they can do.
Finally, there is one thing that I am absolutely confident robots will never be able to do, no matter how advanced they get; science. I mean real, solid, actual science. You simply cannot program for curiosity, and the ability to creatively act on that curiosity. No matter how advanced these robots will surely become, they will not be able to, as per many a science fiction movie, "outgrow" their programming. They will always do what they are supposed to do, and not any more. Science and curiosity are too complex too program for, so robots will never be able to do anything close to real science.
sorry for my inevitably poor spelling and writing, and for sounding like a hyper-conservative old man.