Apple is a company...they do not get profit from merely technical achievement.
Nobody cares if there's a 1GHz iBook if the ad for it sucked. Currently, it's mostly mac faithful who continue to buy Mac products. New users are usually not the ones attracted to the big numbers, but the fact that the Apple brand name means something to them and they like the ease of use and other Apple virtues. If Apple can put a 1GHz 7460 for cheap, they'll do it. But they're not going to bend over backwards trying to do it...Apple and any other company only do things that make since economically (at least, the good companies do
). How much does a G4 800 cost? $300? It's safe to assume that when the 7460 finally makes it at 1GHz it will be more than $300. The G3's are more like $100. How many customers will they lose from G3 to G4? A few. How many by Having the price $1750 vs. $1500? A whole lot. Does not make economic sense.
Apple is a company. So when you're trying to predict it's actions, think like a company does. They're out to make money and please shareholders. Nobody cares how good the products are as long as they sell.