How about Nintendogs?
Really, how many new IPs does Nintendo need?
Mario and DK cover platforming and a multitude of spin offs.
Metroid covers SF advenure.
Zelda has the fantasy adventure.
Fire Emblem for RPGs.
Pikmin for puzzle/strategy.
Advance Wars for traditional strategy.
Excite ____ for racers (Mario Kart, too).
SSB for fighters.
Outside hardcore sports and racing sims, and FPS (which the market is glutted with anyway), I don't see a whole lot of genres that Nintendo can't cover with their existing IPs.