Examples: N64. GameCube.
These titles alone dont sell boatloads of systems. They all appeal to the same crowd. People are consideirng these huge blockbuster games, and they ARE, but they aren't what sold the Wii.
Motion controls are what sold the Wii. Simple as that. Nintendo caught fire. 360 had RROD issues and PS3 was $600. Nintendo released Wii at the right time, with the right price, and a new gimmick. It became "tickle me Elmo-Must Have" type of item for the holidays. A very very rare sales explosion that hardly ever happens.
It was a cheap console/expensive toy for kids. That's where Wii U will be different. It doesnt have that "kids toy" approach. Infact, with it's somewhat delicate Tablet controller, its quite the opposite. I certainly would not want my 8 year old kid dropping that tablet or leaving it laying around on the couch. The batteries won't last long on the tablet control. It will also make the console more expensive, as youre now paying for the tablet aswell.
Nintendo also said theyre releasing summer 2012. Bad idea. It wont catch fire like Wii did for Xmas when it came out and then maintained momentum for a couple years after.
So what will push the Wii U like the Wii? Nothing from what Ive seen so far. I predict it being more like Dreamcast than Wii. Since its Nintendo it will obviously sell more than Dreamcast, but I predict a similar fate. Early release ahead of other consoles, but will be quickly forgotten when the next PlayStation and Xbox come out. Sales will be in the N64 range.