The way I look at it, if the hype is strong within the core console fanbase, then it will reverberate throughout to mainstream gamers and multiconsole owners.
The question I have is, how many GC gamers plan to pick this up on day 1?
I, as a multiconsole gamer, wasn't too enthralled by the first game, and if certain gameplay improvements have been made, I'll pick this up (most likely not on launch day).
I know many Halo fans, that will be going nuts on November 9th. Heck, I memorized the release date months in advance. I don't do that for many games! There are some sites with a countdown until that date (at the moment it's 4 months, 17 days, 18 hours, 36 minutes and 6 seconds until the game is released, according to Xboxsolution.com).
The anticipation from the Xbox fanbase is quite evident. Perhaps it's due to the game being over-due, as it was supposed to come out earlier this year, but nevertheless the hype is there and it's growing.
Also consider that Bungie and Rockstar are doing a good job of releasing info in bitesized amounts at calculated intervals, to help build hype. They are doing a better job than Sony/PD (as far as GT3 is concerned) and Nintendo/Retro (as far as MP2 is concerned).
These morsels will be eaten up by the fanbase, and then the hype will trickle out to the rest of the gamers.