Doesn't everyone in this industry have to always worry? There are always at least three big companies trying to attack each other -- they /should/ be worried. That said, Nintendo has the least to worry about.
Particularly unthreatening is the Xbox 360 price cut. Why? Because Nintendo can't make Wiis fast enough to sell them despite outpacing Microsoft and Sony very significantly in production of Wiis. And, further, Nintendo could afford to drop the price of the Wii at least $50 and still make a profit on every unit sold. So why on earth should they worry about the 360?
The biggest thing Nintendo needs to worry about is how much money they're leaving on the table by shipping only about 1.8 million units per month world wide. If Sony and Microsoft had a problem like that, they'd be celebrating.
I mean, if they could also be making money on each console sold...
