3D without glasses from a flat panel display is possible, but not without kind of sucking unless someone invents a completely new way of doing it. The panels exist and have for a few years, but they use frensel lenses on top of the panel itself to try and separate the light from each alternating column of pixels in different directions so that you can view a different image in either eye (made of a collection of columns pointing generally in the direction of each eye). To create more than a single viewing spot that works there are several "left" and "right" lenses at slightly different angles (say four in each direction) The problems with this approach are numerous:
Because the light is beamed out in somewhat parallel columns, the effect only works at certain distances and lateral positions in front of the set. Your eyes have to end up in a position that happens to be aligned with the output of the panel's intended images for each eye (left image to left eye - right image to right eye). Further, most of the time you can see more than one "copy" (several angles of right image for example) so you get terrible ghosting of the image. Also, if you move your head left or right then you will swap eyes (left image to right eye, right to left eye) which scrambles the 3D effect and makes the image unwatchable. You also have to divide the resolution of your panel by the number of angles you beam out - for example, a 4K HDTV with ONE viewing position (2 lens angles, one per eye) would output 1920x1080 per eye, but only for one person in one location. Most of the panels have at least 4 angles per eye, so divide your effective resolution by 8, this means you need a 16k panel for four people to watch autostereo (no glasses required) 3D at full HD resolution, and then it would still have ghosting and they could never move their heads.
Most of the manufacturers I've talked to don't really see it as a solution for home viewing, but rather for digital advertising signage, because as you walk by the displays they do grab your attention. But their limitations are more than anyone I know would put up with in a living room display. For now shutter glasses are the best solution for home use.
Also, a lot of the eye fatigue that comes from watching 3D is not because of the glasses - it is because most cinematographers don't know (or don't care) how to compose stereo movies so that they DON'T cause eye strain. When you have lots of extremes in your 3D scene (like a T-rex or Scrooge's nose poking you virtually between the eyes) your eyes get fatigue because in the real world you don't spend 90 minutes focusing on something that would make you cross-eyed. When objects are composed at or outside the extremes of what the average person can comfortably focus on it causes severe eye strain and that will give you a headache. Movies like Up or Avatar don't do this (at least not all the time), and most people are fine watching them without discomfort.