Well, they are all fads by definition, but that isn't nearly as negative a term as it is taken as. A fad is only something that booms in initial popularity but falls back down to earth over time. This says nothing of the quality of the fad, only that it will eventually be required to stand on it's own and not just it's popularity over time. Gimmick on the other hand implies only an illusion of quality by the inclusion of more and more "meaningless" features -- I sort of see 3D in that light, but not motion controls. Motion controls still have far to go, and I can think of several applications when paired with other theoretical products that we'll hopefully have in the future.
Even currently, I can think of several ways that current Wii controls could be used, but aren't at the moment in any game that I know of. Yes, there are games that cannot exist without these controls and I can see them being incredible.
Yes, I'm also being purposely vague because I still have pipe-dreams of creating these things myself, hehe.
3D on the other hand excludes too many people to be meaningful to future generations. There may be a handful of good 3D games, but when the fad ends, I don't see it going far.
It's been said before, but HD is gimmicky, but not a gimmick by nature nor a fad. We're always going to be looking for higher definition displays because clearer graphics are always going to have greater potential immersion by giving you clearer graphics at larger resolutions. Blurry, muddy textures do distract, though HD will only flaunt poor design wherever it appears.
For sake of TL;DR, we're done here.