The carts are already plenty small. Yes, they could be smaller, but any smaller (without being downloads only) and they'd be difficult to handle. For cost, the

The carts are already plenty small. Yes, they could be smaller, but any smaller (without being downloads only) and they'd be difficult to handle. For cost, they could likely reduce the pincount for new cartridges, by changing the number of data pins, but that doesn't preclude using the same slot. Reducing cost of cartridges is more effective than reducing the cost of the console. Reducing pin count would probably save more money than shrinking the small amount of plastic case. For energy efficiency, maybe they can eliminate 3.3v and only keep 1.8v for new carts, maybe redesign the insertion detection pins to detect old and new.