Until they do some hologram-like thing with perfect fluidity and color, 3D will remain an enthusiast thing, by and large. People are not going to walk around with headgear or goofy eyewear in their living rooms. This is not like going from B&W TVs to color, or 4:3 NTSC to 16:9 ATSC. Neither of those transitions required anything new from the viewer. Watching a 42" plasma is every bit as passive as watching a 13" scanny B&W CRT.
I'm very skeptical about any current tech to produce 3D without dedicated eyewear. I'd love to be proven wrong on this.