Gamecube console hasn't been as successful as Nintendo expected, barely fighting the #2 spot with Microsoft giant, both companies are still far away from Sony in the race... perhaps this facts started a rumour around that Nintendo could be taking Sega's route in the next few years leaving the hardware market for dedicating to games development (though all Gameboy incarnations have been extremely successful).
IGN however has the news that Nintendo has made it official, they aren't leaving the console market anytime soon and actually are already planning their next-generation console expected for 2005, when Sony and probably Microsoft will have their products ready for consumption, too.
This quote should say it all: "When we withdraw from the home game console, that's when we withdraw from the video game business."