GameCube could've stolen a lot of support from the PS2, the problem was it launched too late.
By the time the GCN came out, the PS2 was already clear like 20 million worldwide, thus rendering the fact that it was easier to program for a moot point for most devs.
If Nintendo had moved up their hardware time table by a year (GameCube hardware WAS ready for 2000, the games were not) and been better prepared, I think they could've carved out at a minimum a very solid no.2 and probably prevent the XBox from gaining much marketshare at all.
If they could've launched in November 2000 with Zelda: Majora's Mask, Perfect Dark, Madden NFL 2001, maybe like a Dead Or Alive 2 or something, along with some multi-plats, I think they would've done quite well.
