AR and VR excel in different areas. AR is a natural fit for most social contexts because it brings elements of the digital world into the physical world without completely enveloping the senses. VR isolates the senses, which provides deeper immersion. A virtual environment can be similar to the real world or completely removed from it. The rules of the physical world don't apply in VR.
I agree with Cook that AR will likely be more popular in terms of daily/casual usage by the average person, but VR will be just as "huge" in terms of societal impact. And some of his comments about the socially-isolating nature of VR are a bit short-sighted. Facebook (and others) are already doing a lot of work on getting people into shared spaces with high-fidelity avatars that really do give a sense of being with someone who's not physically there.
And with 360° photo/video, volumetric 3D video, 3D scanning/printing, photogrammetry, etc-- we're quickly moving toward a "mixed" reality world where the line between AR/VR is blurred anyway.