I have it coming from a reliable source that CURRENTLY
The Core will drop to 279
The Premium will drop to 349
The Elite will drop to 449
This will clear out the inventory of the Premium which is the most manufactured 360 and the most sold as they know Premium will sell the most until the demand for Elites pick up in 2008. Elites and Cores have relatively the same manufacturing percentage: low at the moment until FALL this year.
When the 65 nm processor falcons are introduced across all SKUs, the holiday season, a month or so after Halo 3 will see the core drop to $249, The Premium will drop to $299 and the Elite will drop to $399
The Core, Premium and Elite Falcons will have a redesigned motherboard which includes HDMI across all SKUs, a quieter DVD Drive and the falcons will STILL have an extra fan heatsink as Microsoft is not prepared to take anymore risks.
The Falcon will reduce the cost to manufacture the Xbox 360 CPU and GPU by ~40-50% but Microsoft will incure additional costs on the new fans and HDMI across all SKUs. Still at the 249,299 and 399 price, Microsoft will expect a profit from the console by early 2008 when the Q4 results are announced.
EDIT: Clearing out inventory of 90nm so they mostly have 65nm on shelves this holiday season