I also think that Sony has a more broad appeal with their internal development process than Nintendo... I think the Wii will be ultra successful, but I think the PS3 can sell to almost similar levels as the PS2 eventually (maybe 100m or a little bit less).
The Wii will broaden the market and have it's own 'casual' 'simple' 'party' game monopoly with the Nintendo fanboy's as well as some others who simply like playing Nintendo games, PLUS people who own it as in the PSWii and Wii60 combinations.
In terms of Sony's broad development appeal... they do things the 'cool' way. Nintendo do things the 'everyone must be able to enjoy' way which cuts out some things from their games that I think COULD make them better... Sony are the type to just have an idea, and make it ultra good, make it the best, drop lots of money in it and bash the crap out of anything else... an example of this from last gen in the GT games, it is known as the standard for racing games, and while other racing games sell, nothing gets to the level of GT sales.
360 IMO is the biggest loser here because it's become to well known as the 'geeks' console... microsoft have done that with the Xbox name unfortunately and it will never have massive main stream or casual appeal... GTAIV however will be a VERY interesting one to watch. Episodic content makes the geeks want to buy the 360 for it, but casuals might not care about either console because the price is too high.
BTW - Excellent discussion starting topic Source, different discussion to the usual HIGHEST HIGHEST HIGHEST... Wii has been WAY to high estimated for WORST CASE scenario.
