1. Avatar's story is just a rip off of Ferngully, anyway: http://rosewest.hubpages.com/hub/Avatar-vs-FernGully
2. There's a huge difference between film CG and in game graphics.
Even if you tried to render a single frame from the original Toy Story now, it would probably still take hours. Film CG doesn't cut any corners. A light is supposed to act like a light and cast real shadows, and shiny/transparent materials are supposed to refract/reflect light as in real life.
No game engine does that. Objects aren't even modelled most of the time, they're just simple flat polygons with textures on. In film CG, everything is actually modelled and given a material with it's own properties, rather than a texture. In a game engine, corners are cut to get something that looks realistic enough, but requires minimal processing power.
You might get 100k polys on screen at one time with no effects and a short draw distance in a current gen game, but in film CG you might have millions in just a basic shot. Characters are also pretty basic in most games, but in film, they have a whole load of complex coding to handle simple things like 'tummy jiggle'.
I'm sure millions of polys on screen with full shadows/anti aliasing/reflections/caustics/depth of field/motion blur/etc is capable of being rendered at upwards of 60fps, but probably not for the next 15-20 years, at least.
