A trailer this October wouldn't be unusual but it would be unlikely.
The way I see it is that if Nintendo talks about Zelda before one of the already announced triple A games (Like Galaxy 2, Metroid Other M or even Red Steel 2) gets released then that would undermine those products.
Zelda is an unrivaled series within the industry and any tidbit on it would be a show stopper for anyone sharing the same stage.
With the new game, Nintendo has consistently been quoted as saying that they want to outdo the highest rated game in gaming history. Zelda Wii will be measured against other adventure games such as Mass Effect series, Bioshock series, ElderScroll series and the like.
You can't outdo the finest in the industry without investing more time and money then your competitors who are also trying to achieve the same thing but on superior hardware.
Off topic, but I feel that the
TP 2004 trailer and the final game did have many and significant inconsistencies. However,
TP is a great game by industry standards and I can't go against that.