DPI can be a measure of resolution depending on how it's used. I wish folks would stop referring to screen resolutions in DPI, the more correct term is pixels per inch. (You won't dpi in Photoshop for example.)
Bingo. And that right there is what's so confusing about Apple's "retina" terminology. The distance someone is viewing the display has just as much to do with what resolution the screen is and what size it is. People made the same argument over whether a 720p TV is better than 1080p TVand at what screen size it made the difference.
A higher resolution iPad should be better but in practice it'll depend on the content. It also remains to be seen what Apple will price this new beast at as wellthey could conceivably keep the iPad 2 alive, reduce its price point a bit, and offer the new iPad at a premium to differentiate it.
You misread/misunderstood my post. I said "high res enough for the screen size", meaning enough pixels per inch ("res" for "size").