I believe the GameCube has been out for over a year in Japan Bond... Not that it had a good launch in Japan but at least it was better than X-Box'.
I would say that GCN has been doing better than X-Box without Rare so it wouldn't make a difference, but I know that M$ will expect Rare to make games for them.... so you can't say that yet.
I still wonder if Nintendo owns the license of Perfect Dark... I'll check the boot-up screen the next time I play it (prolly within 15 mins).