The only slight flaw with Yamauchi's point in retrospect in that a lot of that audience is very fickle. At the time he was completely right to say it and Nintendo certainly reaped the benefits from this strategy. However, the question is what's left for them to innovate on?
VR tech isn't ready, I'd say people are largely over motion controls as a USP (in that I'd argue that once the blue ocean audience have had that experience with Wii, they won't pay for it again but prettier) so WiiU was always likely to be stuck between a rock and a hard place tech-wise. Of course there is the recent tablet trend which they tried to ride, but the fact is people had been playing with touch for nearly a decade on DS and that many people already owned some sort of touch phone or tablet which could do that so there was no novelty attached to it.
It goes back to Gunpei Yokoi's philosophy when designing the Game Boy - using familiar tech in new ways. The problem is what happens when they miss the boat on that tech so it becomes more mundane, which is what happened with WiiU and now they're forced to wait for the next one which may come who knows when?
You can argue that Sony and MS are far more conservative and they probably are, but that's because their 'hardcore' audience is much more reliable. Nintendo have become forced into an all or nothing strategy, when it works they absolutely dominate, when it doesn't they end up with a WiiU or GCN on their hands