Just posting because this is somehow unprecedented. Nintendo's home system ecosystem totally collapsed. I don't think many actually realize how crazy is this scenario. Even by considering Wii was based on casual audience - going from 100+ million system sold to....few millions is incredible.
It's obviously the combination of many factors, that reinforce each other negatively, including (a) price and little flexibility in dropping it; (b) lack of games; (c) long times between major releases; (d) total lack of third parties; (e) lack of proper online infrastructure; (f) lack of a major interest in the tablet, since tables are everywhere around us; (g) bad word of mouth by gamers and press; (h) lack of proper marketing; (i) confusion because of the name - people think it's a Wii extension somehow; (l) lack of innovation - the system doesn't bring anything interesting or different like, e.g. the Wiimote (this point is particularly incredible - coming from Nintendo especially).
Nintendo made all possible mistakes that could have been made - I can understand gambling on some of these factors, but hitting the negative target on each single of them is a total lack of proper R&D consumer research and system development. It's lack of professional attitude. Wii U was launched on the hype of the iPad and not considering the volatility and competition of is latter market, where everything gets copied really fast, consumer changes product every year and innovation vanish so quickly. Not a good basis for introducing a 5+ year home system. Nintendo's execs overestimated themselves because of DS and Wii's overwhelmingly successes - which, yes, were well targeted and constructed products, but that also benefitted from a certain fraction of coincidences and opportunism. Nevertheless, it's alright to recognize Nintendo's merits with DS and Wii - I think they offset what came from pure luck. Too bad this blinded them considerably afterwards.