At E3 one year Shiggy made a comment to the effect of "Mario will never beat up a hooker" emphasizing that Nintendo's focus was making fun games that everyone could play. When they say everyone they mean making a game that everyone, including your baby sister to your grandpa, can enjoy. They don't mean making titles specific to any one age group or demographic.
Take Two may very well be making a Wii game, it may even be a more mature themed title, but I highly doubt it would be a GTA title.