i think the biggest reason for Red/Blue doing so well was because everyone had at least one Gameboy. The DS is selling like mad, but I think it will take quite a bit of time to hit Gameboy levels. Not only was Pokemon way more popular back then, but the Gameboy itself was far cheaper than the DS. My prediction: 15-17 million. So it'll do better than Ruby, but no Pokemon will ever beat the originals.
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
Essay Pro