Its broken logic based on personal impressions.
While i am no halofan myself, i know its a huge title in america.
Halo 1 was the 8th best critically acclaimed game, EVER. Halo 2 is the 20th best ever. As a game series, no other games except for GTA has 2 or more titles in the top 20.
It sold what? 7-8? million copies, for a total of 20 million xboxes? 30% of all Xbox owners bought Halo. Halo 3 will have the biggest marketing budget EVER, for a video game. This is MS' baby, the name most commonly associated with the word xbox. It will have enourmous hype, commercials alone will see to that. Halo 3's marketing budget is probably bigger than most exclusive titles has for a total budget.
Its ridiculous to say that Halo 3 will not move consoles. Unless the game is completely broken, it will sell consoles. It may suck, and marketing alone will move a ton of consoles.