4(iPod touch and iPhone), 7.85, 9.7 = Apple trying to do to tablets what they did for MP3 players.

Dominate every possible price range with a slightly more expensive and greatly superior product. Dominate the supply chain and maximize profits. People are willing to pay the $100 premium is Apple makes a better product (No, I don't want a iOS vs. Android discussion here).

I'd say, the 7.85" is coming out soon. Also, the PPI argument has been out through DaringFireball for months now. This isn't a recent find.