PS3 has already proven that a small percentage of consumers are interested in 3D.
Will 3D itself sell the portable device, at first, yeah. But I think it will depend on the game library in the long run.
The 3DS is more powerful than the DS, so you'd hope that library is a notch better than already established DS library.
I am the black sheep "of course I'm crazy, but that doesn't mean I'm wrong."-Robert Anton Wilson