Firstly, Google has Glass, self driving cars, Google Fiber, Loon, and every single one of them has the potential to be the most significant thing of this century - though these are mentioned in the article, their potential is __highly__ underestimated. Its true some of them will (I prefer might) turn out to be duds, but definitely not all of them.
Secondly, all three companies make a conscious effort to be innovative. Sometimes they err on the side of innovation. And the smartest brains are still proud of working there. And until that changes, one can argue that with the recent deluge of startups that it has, they will continue to dominate.
And talking of AI, I guess almost all the leaders in the field are have a strong relationship with Google. Andrew NG, Sebastin Thrun, Peter Norvig, Ray Kurzweil...