At the moment, while the Internet is pervasive, for every person online, there are two who are not. However he thinks that by the end of the decade, everyone on Earth will be connected. The number of people online is expanding dramatically, in particular with the spread of mobile phones. These are enabling parts of the world to become connected when they would have been forced to wait for landlines.
Of course if he is right then Google’s advertising supported model will do rather well. Poorer nations will probably be OK with advertising if they get free services. However 2020 is still a little tricky given that a large chunk of the world does not actually have electricity yet.