This is an interesting question. MS is really in the driver's seat here. Not only do they have a vastly better cost structure, they have a massive source of additional revenue in Live and a second, highly profitable hardware piece in kinect. The calculus for MS becomes very interesting when they balance lost hardware profits with increase software sales, royalties, and Live revenue.
Sony is between a rock and hard place. They probably aren't making any money on hardware on a fully loaded basis (on a manufacturing cost alone yes, fully loaded probably not) right now so any price cut will dramatically impact the bottom line in the US.
Nintendo is making massive bank on each Wii and still selling tons so they probably won't want to cut either.
All in all, it is not a foregone conclusion that any of the consoles will see a price cut. There certainly isn't a clear strategy reason to do so. Without access to internal numbers, there is no way to tell the optimal response for each company.
