Finally someone put this in a very well, articulated post! A few things I would add are that theoretically, you could use a handheld in conjunction with the console in the same manner you use the gamepad on Wii U or stream MP content w/DS/3DS. In other words, one game (ex. Mario Kart) can be do local multiplayer across multiple devices at the same time like you can on DS/3DS. Another example would be asymmetrical multiplayer (NSMBU) where a completely different type of gameplay could be added into the mix if someone had a handheld and console. Also, as far as gamesaves go, cloud saves would be nice and should be included, but there's no reason the devices shouldn't be able to perform updates with each other locally. In other words, an internet connection wouldn't be a requirement for transferring saves from one device to another. A proper account system would be ideal as well as the option for physical media. One last feature that is paramount is the architecture itself. If Nintendo did this right, all of these games would be backwards compatible on future systems. That means they don't have to constantly port their back catalog each time they come out with a new system which in theory should increase their sales.