Again, just some random thoughts. I’d like to think Nintendo is secretly working on a mobile phone that we’ll see a few year later. (See: Xperia Play)
After seeing the size of the Nexus 4 in person, I say it could be very possible. A 4” screen with speakers on the left and right (while in landscape). The screen can slide out to reveal the controls and a second screen (to allow for the DS style). Move power button to the side, keep the depressed thumbstick (and add the second one on the right side) Add a dedicated camera button that takes a photo when used as a camera or a screenshot of your game as you’re playing games.
Software would be interesting. Answering a call while in slide out mode answers in Speakerphone. Sliding close while incoming call answers in handset mode. It could put your gave in a save state, similar to that of the 3DS when you press the Home button. The current 3DS layout could still work. Just move all the navigation to the top screen and call tell when you’re in portrait or landscape mode. The information bar at the top of the current 3DS could easily be changed into a notification bar with slide-down options.
What about physical games? Obviously the full-sized DS and 3DS carts won’t fit in a device like a mobile phone. Much like the SD Card, they’d have to switch to a micro format. That’s if they still do physical carts. That’s a lot of cards, though. microSD card, micro SIM, and a micro Game cart. Would there even be enough room for all of those cards? And those with existing games? That’s a tough one. Some kind of digital trade-in program? microSD cards have a 32 GB capacity (using the SDHC standard), so that wouldn’t be much of an issue. Using the SDXC standard (which supports up to 2 TB) might be costly. The device could also have built-in storage. I’d say 8 GB at minimum. 4 GB minimum might be pushing it.
I wouldn’t expect top-of-the-line hardware in here. Hardware that’s just enough to make the system last at least 3-5 years. (You know… until the Lite version of the Nintendo Phone comes out.) A just good enough camera. It would have to be LTE out of the gate so that it’ll always support newer current phone standards throughout its life. Naturally, it’d be a little thicker than the thins phones we’re use to but I’m sure it’ll be worth the trade off to have physical controls.
Obviously, this is just fantasy land dreaming here. But if Nintendo wants to survive, the next on-the-go gaming device must have communication means in it.