I did a research, and I think you're right, the beta screenshots from OoT were of a game that never came to be (Zelda 64), my mistake. And i'm not saying they will change the cell-shaded graphics, just adjust them or give them more contrast.
I agree that the graphics are good, I like them and I consider them relistic and colorful but don't you remember Beta videos of OoT and TWW? they are completely different from the final release, I'm just saying it is a possibility.
I've been thinking, maybe the cell-shaded graphics are from the beta release or the demo that is playable at E3, because I remember reading on an interview that Miyamoto said:
This led me to think that the semi-Cell-Shaded graphics aren't permanent. Personally I liked them, I think they're a...