Peter is pretty much on the money here. Google's biggest (search engine) threat is Facebook if FB can get their act together. Second is Amazon since they can be a one stop shop. But his comment came before the AI 2nd revolution hit mainstream which has changed R&D at all of the tech companies. Google does have some problems though, it can't go to far down the DoD, Darpa route since Googlers don't want to work with the military (as the article describes) and then it may miss out on innovation in China by not having a Chinese presence and offices in China to get at that talent. That ship may have sailed though as Alibaba and Baidu are giant. What Google really needs to do is unleash its human capital.
