From the article CONSOLE PRICE CUTS: THE EVIDENCE the percentage of systems sold at a given price in the last generation was:
And the Average Price people bought these consoles at:
One thing to notice is that previously most sales have happened after the first price cut when a console is under $200; and many (if not most) of these people who made these purchases are willing to wait until a console becomes affordable to purchase it.
I could be wrong but I suspect that a console priced at $300 or higher will never be considered by more than about 25% of gamers; it doesn't matter how good the games are, few people are willing to spend much more than $300 for a gaming console.
What we know about the XBox 360 is that (in a very real way) it is a $400/$500 gaming system which prevents it from being a marketable product to the majority of gamers. A $100 price drop would give them an opportunity to sell more units; a $200+ price drop would put them into a range where most gamers buy their videogame systems.
