Why hello there. I'm XBebop, presidential candidate. Nah, just kidding... i'm just some random nerd making predictions about economics on a forum!
The Wii was the leviathan of the industry in 2007, and I believe it will continue to be so, barring nuclear war, in 2008. As of right now, the maximum the Wii could sell is 21.6 million consoles from January 1st through December 31st. But if Nintendo ramps up production due to demand, it could reach 25-30 million dpending on what time of the year production is increased.
There is, in my opinion, no reason for demand for the Wii to slow down in 2008. Nintendo has a slew of gargantuan titles coming out early next year: Super Smash Brother Brawl, Mario Kart, and Wii Fit come to mind. Not to say there won't be a surprise hit such as No More Heroes. Also, Nintendo has yet to do any of these things to increase demand: Lower the price; release new colors; release a new, larger bundle pack.
A WiiFit+WiiSports+Wii Console bundle might be in order for this year. If so, I expect casuals to eat this like Rosie O'Donnel would eat a fat kid; or a cake. Yes, a cake.
Software Expectations:
Super Smash Brothers Brawl: Given that its predecessor has sold approximately 6.58 million copies on the much less popular Gamecube, I believe this game could pass 6.58 million copies by the end of this year alone! Don't quote me on that, though. I think that anywhere between 3-5 million is much more reasonable. I'm no John Lucas. ;) (Legs of the Gods)
Wii Fit: This game is an exceedingly tough one to predict sales for. It could either be the next exercise craze, or it could flop like a magikarp. I'm expecting 2-3 million. But that's only because i'm a coward. :P It could do 5-8 million, but that's only if the advertising is the best it could possibly be. (Maybe give away a Wii and Wii Fit to an entire audience on Oprah?) If this game catches on, I expect it to have Pokemon Red/Blue legs. As in Energizer Bunny type legs. Of the Gods.
Mario Kart Wii: The previous console installment of Mario Kart was a bit of a dissapointment compared to the rest of the series, acquiring sales of only 6.6 million. But, its handheld brother has since then had a game sell 8.18 million worldwide, so the Mario Kart name has in no way diminished in the past few years. I expect this to sell 4 million in 2008 alone, and have the legs of the Gods for the rest of the generation.
I may or may not update this later with more predictions. Thank you for reading this extremely well-written thread. Notice my ego? Thought so.