story
There shouldn't be one game per franchise per platform...
But... they have more than "The Triad". To plagarize someone else:
> Nintendo has Zelda (action/adventure), Xeno series (JRPG), Fire Emblem (SRPG), Mario (Platformer, Kart Racer, RPG, Sports), Pikmin (RTS), StarFox (Dogfighter, on rails shooter), Splatoon (TPS), Kirby (Platformer/Action), Animal Crossing (Simulation), Pokemon (JRPG), Metroid (Platformer/Shooter, FPS), Smash Bros (Fighter).
If they could release those on a regular schedule AND stoke the fires for 3rd party? And damn if being based on Unity won't kick THAT fire... They will own the next few years.
You think they will want to be limited by someone else and give up that freedom? Didn't work out real well for Sega...