Second, and I think perhaps more fundamentally, Google is incredibly well diversified among ad channels, so I think lumping that all together and then drawing the conclusion "Google is at risk because they get all their money from ads" misses the mark. Google has AdWords, AdSense, DoubleClick, YouTube, Android, GMail, Google Assistant/Nest, etc. They may be dependent on ads but they control a staggering breadth of ad channels.