Just because someone is a casual does not prevent them from getting a game on day 1. Casuals get hyped like core gamers do, however it is by different methods and marketing tactics. Look a summer movie blockbusters.. I do not think those people who went to see Transformers in drove last summer were all Core transformers fans, they just wanted a cool movie.
End of 2009 Predictions (Set, January 1st 2009)
Wii- 72 million 3rd Year Peak, better slate of releases
360- 37 million Should trend down slightly after 3rd year peak
PS3- 29 million Sales should pick up next year, 3rd year peak and price cut