The way I know it, an image specifically made for 3D won't work well in 2D environment.
The only way to appease both markets is to render 2D environment in 3D, that is, simulate 3D with 2D materials. To achieve maximum result in stereoscopic 3D, a game needs to be made with 3D in mind (and, tested with 3D hardware too, now that's something I'd like to try)
I think you are mistaking film tech with game tech. 3D Vision, like the other 3D solutions, use z-buffer values to calculate depth. This is inherent in all Direct X games and helps the characters render correctly on screen (shadows and size are correct with depth). In other words, gaming 3D is actually built from the 2D!
Rendering 3D thusly does have its issues. Sometimes, every now and again, devs set the game's skybox to near which makes the sky look too close. Fortunately, most companies do it correctly, it makes sense to set the skybox further out than a building. Unfortunately Beth is one of the few companies that sets the skybox too low. Luckily Beth have so far used meshes that can be edited to push up the sky box. Totally fixing the problem.
As a previous poster says, one of the joys of jumping on the 3D bandwagon replaying your old games. The oldest game I have which looks good in 3D is Project Nomads 2002!