The day Zelda goes down 'steampunk' is the day you see it fall down the same path as Final Fantasy. Focusing on graphics and storyline and losing more and more sales each title.
Spirit Tracks looks good simply because the train is just as Aonuma says, a means of transit and a story device. Not something the entire game focuses on and something that changes the feel of the entire game (aka, makes the games style focus on a new genre or platform).
Part of the reason I think Twilight Princess saw mixed reviews and fan support is because the focus was so much on the 'style' and graphics. If a Zelda went 'steampunk', or any other style besides what they have been in the past, ultimately that's the path the series would be forced down. And Zelda more than any other series is rooted in its past.
Six upcoming games you should look into:
