Consumer trepidation aside, one of the other major issues standing in 3D's way on its march into the mainstream is high production costs. 3D typically means two lenses, but one company, ISee3D, may have perfected a way using just one.
In theory, ISee3D's technique is mind-numbingly simple in its execution. According to them, one need only cover up one half of the camera lens, which shifts the focal point, and then cover up the opposite side of the lens, shifting it again. Rapidly alternate between the two sides and voila, two images of the same subject from slightly different focal points and a 3D image. Sharp's glasses-free 3D parallax screens, deployed in the upcoming Nintendo 3DS, operate on a similar principle thanks to their shifting images.
Of course, this is but one issue in a long list of issues presently plaguing 3D adoption. Shifting lenses aside, those glasses... they still just won't do.