Since Nintendo makes money on hardware sales, and is the biggest publsiher of games on it's own systems by a long shot they'll always do well for that alone. They system would have to sell so poorly that they didn't recoup development and marketing costs. And honestly I think even if they made a system that only played their own games I still think they'd turn a profit. I'm not saying that would be wise, or make them rich, just that they are powerful enough to pull that off(escpecially in japan these days)