I assume by "Wii" you mean "motion controls", because by your list, all consoles are fads, since sales of all consoles go down and decline after a certain period of time.
As for the question is Wii a fad? Not at all, in terms of Home Console success. The Wii is still Nintendo's most successful console in its sixth year. Hardware and software sales are lower than the PS3 and Xbox 360, but not that much lower. Just Dance 3 was released a few months ago, and is on track to sell over 10 million, it's the most successful title in the franchise history which is very specifically a motion controls game; and the Wii version is the one people are getting, not the Xbox 360 or PS3 version. The Wii is achieving this with sparse software releases and a new console just over the horizon.
Lastly, motion controls are now a feature of every single new console, both home and handheld. That's not a fad, that's a trend.
I describe myself as a little dose of toxic masculinity.