Um, no. Cameras shoot on the film they are designed for. 35mm film has a native aspect ratio of 3:2. Widescreen film is done with anamorphic lenses (which squish the images horizontally) on the camera and projector. Widescreen films really got their start in the '50s when TV was first threatening cinema.
Actually, silent film had a standard aspect ratio of 4:3, or 1.33:1 (as does Super35 4-perf). When sound tracks were added to the film, the image frame had to be adjusted, and the Academy of Motion Picture Arts and Sciences decided on an image frame with an aspect ratio of 1.37:1, known as the "Academy Ratio". Thus the NTSC TV standard chose an aspect ratio of 4:3 as it was the same, or close to the same, as the aspect ratio for most films.
http://en.wikipedia.org/wiki/Academy_ratio
When cinemas switched to widescreen, they tried a lot of techniques, but the two standards that developed was either anamorphically squeezing a 2.35:1 - 2.40:1 image onto the 1.37:1 frame, or cropping the 1.37:1 frame, typically to 1.66:1 or 1.85:1.
Note that I'm talking about
standards for 35mm film. You could theoretically shoot a wide range of aspect ratios and image frames on 35mm film. However, most films stuck to the standards because that was what could be realistically projected on the most screens. For example, while most 35mm film standards run the film vertically through the camera and projector, VistaVision was shot running the film
horizontally through the projector, at an aspect ratio of 1.66:1. However, most movies shot in VistaVision were projected from prints made to standard vertical 35mm film. As far as I know, there was never a film standard with a 3:2 aspect ratio.
In regards to transferring old TV shows and movies to HD, it's true that typically those that were shot on 35mm film had more
detail on the film then could be shown in standard definition (SD) TV. Going back to the film sources and retransfering them to an HD format thus regains detail. However, these new transfers can't get an new image outside of the original image frame, so in most cases, changing the aspect ratio (say from 4:3 to the 16:9 of HDTVs) isn't possible without losing some image.
For video games, it's very different, since in most cases there's no pre-defined image, and most of the on-screen image is rendered
on-the-fly. This is how games offer different resolutions. They take all the individual elements and render it for the given resolution as the game is running. So modifications like higher detail texture packs and higher resolutions are possible. The game simply takes the new elements and generates it for a new resolution.
For a change in aspect ratio in the game, it's a bit more complicated, but typically because of the UI. The UI may have been designed to fit a 4:3 frame, so rendering it in 16:10 or 16:9 may cause a UI element that is intended to appear in a corner to appear more in the middle of the screen. Still, mods are possible to re-arrange the UI for a new aspect ratio. As far as rendering in a new aspect ratio goes, the closest comparison to film would be some of the CGI Pixar films, such as A Bug's Life, where they went back an re-rendered some shots for the 4:3 "Full Frame" DVD of the film. in this case, the computer elements were always there out of frame, they were just re-rendered for the new aspect ratio.
