I think the dipping sales of the Wii are good indication that people are done with motion controlled gaming. If anything, Kinect is the next step...
This re-launch is just going to be a waste of time and money for Sony. They should focus on more integrated gameplay between the Vita and PS3.
There is a difference between the death of a fad and a genre finding its saturation point.
Designer jeans became a craze unto insanity in the late 70s. They've made tons of money ever since be nothing like the fever pitch of that era. A good new Mortal Kombat title can make good money but is unlikely to match the fervor of when the SNES and Genesis versions came out, marking when the launch of a big game title was comparable to a major movie's opening weekend.
The big problem with the Wii is that it depended too much on new hardware sales because the software attach rate was lousy, especially for those people who didn't care about the big Nintendo franchises like Mario platformers. These people were content with Wii Play and a few other items, with no more purchases ever. They got a worthwhile novelty for their money but didn't produce the ongoing revenue stream Nintendo expected. When the hardware sales peaked it meant a huge hit on revenue.
But that doesn't mean the death of motion controls. It just means a hard lesson in expecting them to be the primary basis of a platform. It is a subset, just as connection between a set top and a mobile platform is a market of limited value. Sony will do both to the exclusion of neither and neither overwhelming the core products.
I personally have no use for sports games. I cannot image why I'd pretend to play a game on a computer that I wouldn't play for real. And if I liked to play for real, why would I bother with the fake version when I can have so much more experience from the real thing even if I'm bad at it.
That said, the platform company that ignored the market for sports games would have to be run by monumentally stupid people. Invest to support people looking to spend money on a particular thing in proportion to their numbers.
If I thought I needed to get out in the sunshine I'd play Boktai.