I have a theory that the reason MS didn't show anything at there conference for 2008 is because they're already migrating developers behind-the-scenes to the Xbox 360 successor. MS has shown a fantastic willingness to cut bait at the first sign of trouble and their PC-centric origins seems to have convinced them that might makes right.
With the recent hardware issues on 360, I expect them to call a mulligan and start over in a new generation rather than try to actually work things out. The more PS3 games start to look better than 360 games, the more they'll feel pressure to "jump ahead" again.
They've never given developers that "grace period" at the end of a hardware lifecycle to churn out awesome, omega-generation games (
PERSONA 3 
), so why start now?
If at first you don't succeed, try, try again! The more times you try the more chance you have to get things right!
The question is, what year will Xbox 720 / Xbox Wonderful / Xbox 3 be
on store shelves available for gamers to buy. Not the first info from MS but actually a retail product. VOTE!