What about the 7th category, the consumer that is tired of having his wallet savaged by the four major carriers. Android offers users the opportunity to buy a high-end device, off-contract, for $350. You can then use this phone with a pre-paid service that costs 1/2 of what the major carriers sell.
Maybe its a small demographic, but it seems like its growing.
Maybe even less if you can time it right. When the Nexus 4 went on sale last year for $200 (8GB) / $250 (16GB) USD last year, I debated it for all of about 10 minutes before buying one. If the N5 goes on sale this year to clear out the inventory, I'd consider that a very good value as well.
Maybe its a small demographic, but it seems like its growing.