Both sound and color were possible LONG before they were widely adopted in film, just like 3D. So the analogy doesn't really hold.
Furthermore, 3D really requires digital capture, digital post and digital projection to be practical -- all of which we have now and didn't 60 years ago. From where I'm sitting, more and more films have a 3D release today, not less, and there is no sign of that stopping.
Color and sound are rather natural phenomena and don't require any artificial apparatus to experience (i.e., glasses). Stereoscopic 3D (which, I might add, is NOT really 3D.... but I digress..) not only requires this, but is itself an unnatural experience because it's basically tricking your brain into seeing something that isn't really there by artificially forcing your eyes to see completely different images. That's why it's physically uncomfortable for many, especially over the length of a typical feature film. I wouldn't call seeing color or hearing sound (even when it's rather loud) unnatural or physically uncomfortable experiences, so I just don't see the similarity.
I'm not making any predictions about the future of stereoscopic 3D, I'm just pointing out that these comparisons don't really have much merit.