My anecdotal evidence (aka the best evidence) shows that nobody I know plays games on a console anymore. They play games on smartphones and tablets. Some are heavy users, others can just play 15 minutes of Bejeweled and get their gaming fix that way.
The death knell will be when Logitech releases that iPhone controller. There's still a subset of gamers who hate playing touchscreen games (myself) and with that barrier removed, even more people are going to start moving over. Also as Google Play continues to get better, that is going to continue the erosion of console gamers.
Not that the Wii U would be any less fucked had none of this been going on. Nintendo shit the bed on this one, regardless of how many iDevices and heat waves strike it. If I was Iwata, I'd be fucking embarrassed at those results.