Adding more stuff (aka HD space) for the same price is probably going to be the better model for Sony and MS.
Or rather, MS can merely keep adding gigabytes to the Elite model, and eliminate the Arcade model in favor of a $100-150 "RROD-Replacer" model that's just the base unit with no cables, powerbrick, controler, or faceplate.
$300 is the "sweet spot", and will remain so until the replacement generation of consoles is nearly ready to ship.
As for Nintendo, a price cut to $150 isn't that bad of an idea. In lieu of that, they should start packing in goodies like a 2-gig SD card and/or a second Wii-Remote+Nunchuck set.
Luckily for Nintendo, DSi-XL is probably going to sell pretty well, if not far better than DSi-small is doing.
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