There is a big difference between old style 3D (that games have had for dozen years) and stereoscopic 3D where your brain captures the depth because each eye sees a _different_ image. Seeing depth makes it a much more involving experience.
Most people instinctively say "no". But the reality is that there are far more cues for depth than just stereoscopic vision. Someone with one eye still perceives depths by judging relative object sizes, changes in focus and subtle changes in objects when we move relative to the object.
Head tracking will almost certainly play a big part in coming 3D techs (with or without stereoscopic tech). Add to this eye tracking to adjust virtual focus, and you start to get "real" 3D. One day!