With iPhone you also have a rip-off price to pay every month. Also, where do you see them for $100? The low-end model is the 16GB model and that is $200.
Game Gear failed because it took 6 batteries and last about 4 hours (Game Boy Classic took 4 batteries and lasted about 10 hours, sometimes more). Lynx just had severe lack of games, cost twice as much (Game Boy was $90, Lynx was $180), and not in as many stores.
Minor, but the Wii price at launch was equal to $214. As you mentioned, they also included Wii Sports with it outside of Japan, and the game went for about $60 in Japan.
You don't realize, but you are proving my point. Over time the price difference has gotten bigger. The DSi XL is about $40 cheaper. A $250 pricepoint is the most probably pricepoint and the odds on favorite. I would be willing to bet you on it.
The price drop is almost certain (based on timing) to be based on lower predicted earnings this holiday, not 3DS coming out in February. And you again say the stock plummeted. I disagree. It did drop, but 9% is not what I would consider plummeting.
As for who buys the DS, pretty much everyone buys DS's. Casual gamers, hardcore gamers, kids, adults, men, women. And there are games for all of them. People said the DS wouldn't sell at $150 (their most expensive handheld to date), it did. They said the DSi wouldn't sell at $180, it did. The DSi XL will still sell very well, especially with all of the stuff confirmed to be included with the system.