I think if the Wii U fails, it's far more concerning to the industry as a whole than just Nintendo. Nintendo at least has proven they can sustain even poor sales, as they profited even from the dismal performance of the Gamecube. However, the industry is going to see major decline without a Nintendo console to help bring in the mass market audience. Remember, the Wii was a massive success and the industry as a whole STILL remained stagnant and even reached a slight decline. Imagine what it would have been like without it? Nintendo needs make the Wii U successful because they are the ones who can keep gaming open to the masses.
God knows Sony hasn't been able to do it since the PS2, with their expensive hardware and niche games, and MS hasn't really done it aside from Kinect and Halo, the former of which they have shown they are not serious about supporting. With rising development costs especially from the Sony and MS side of things, and the state the economy is in, people better hope Nintendo does well, as they are the only ones who have been able to keep gaming relevent to the mainstream over the past 8 years or so. I honestly wouldn't be surprised if we are in the early stages of an '83 Atari style collapse in the games industry.