Nintendo better hope the Wii U is not a sprinter like Wii or they are in major trouble, as the sales now aren't even that great.
But that said, I see the Wii U as having more of a traditional curve and be more of a slow burner, not the explosive one like the Wii had, that flatlined. Reasons being, the horsepower is no longer noticably worse, and I also feel that third parties will give it more support, albiet not much more. I also think, or at least I hope Nintendo learned from the Wii and will support it with more than 2 or 3 major games in the console's last couple years. Finally, the price is higher than Wii started at, so Nintendo has more room to drop the price and boost sales a bit more.
Wii U will almost certainly not reach 100 million like Wii, but I still see it reaching in the ballpark of 70 million. Respectable, but not great. It will be the SNES was to the NES; not the phenomenon the NES/Wii were, but like the SNES, will have a stronger and more diverse library when it's all said and done, and more of a core following.
