The computing industry has always sold to segments. Mainframes to large companies, minicomputers to medium-sized companies, PCs first to companies and then middle-class households, and so on. Today, there are around 1.5-1.6bn PCs on earth, of which perhaps half are owned by consumers, yet there are 7.1bn people on earth and 5.25bn adults. PC buyers are still a segment, and a pretty small one, and so, by extension, was the internet.
Mobile is different. It started, like PCs, as a toy for rich people, but in the last 20 years it has spread such that 85% of the earth's population is under cellular coverage - more than mains electricity (80%) and close to the same as access to improved water (90%). 3G networks cover around 60% and will grow to 90% by 2019. Somewhere between 3.5bn and 4bn people now have a phone, depending on your assumptions (there are several billion more SIMs but much duplication). This continues to grow fast, pushing into some very low income groups: the average monthly spend in India is $3-4. In the last decade we've discovered that the value of a phone actually increases as income falls - in the developed markets they sit at the top of Maslow's Hierarchy of needs, but for a poor farmer in rural Africa or an Indian fisherman they solve problems much further down the scale.
Mobile was always somehow separate from the mainstream consumer technology industry - there was always a wall between the two. But since 2007 smartphones have broken that wall down, and the mobile industry is going through a massive category conversion. Of 1.7bn phones sold last year just under 1bn were smartphones, and there are now around 2bn on earth. This will grow much further. The real question will be more about affordable data, and battery life when there is no mains electricity nearby.
For the first time, then, the consumer technology industry is selling to everyone that it is possible to sell to. There are still people who are unable to participate in the economy, but everyone else - everyone able to buy things - will probably be a customer.
This changes lots of other things. Most obviously, as I've written before, it makes the internet opportunity not just two or three times bigger but closer to ten times bigger.
It also challenges conceptions of market size or ecosystem. Since Apple only sells phones at $400 and up (for now) most of this growth in users will go to Android, which now starts at $50 or less. So the Android ecosystem will encompass everything from Instacart customers in San Francisco to ROM hackers in Kiev to rice farmers in rural Myanmar. This makes the concept of a 'customer' on the internet look much more like, say Unilever's: there are people buying soap by the gallon and people buying it in sachets.