1. Additional power.
The Wii U is underpowered, but only just. The Wii U has three possible screens: a TV screen and two gamepads. I want to see all three screens act independently on demand, meaning the TV screen is doing Hulu Plus while one gamepad is browsing the web, another is streaming Netflix. The TV screen and gamepad are used together for a Wii U game while the last gamepad streams youtube. Etc. I'm sure you can imagine a dozen additional combinations.
If you can use all three screens in a single local multiplayer game OR have them act independently like this, internal specs are irrelevant (at least as long as you can still stream 1080p to the TV screen.) You can potentially deliver three times the entertainment of any of your competitors.
2. Cross-function with the 3DS.
Ideally, the 3DS should be able to take the place of a second gamepad (albeit a poor one because of the smaller size.) By the same token, it would be nice if you have a 3DS to be able to play games through the Wii U's much larger screen combination the same way the PSP could be plugged into a TV with cables. It would also be nice for the 3DS to act as a personal save-holder, allowing you to walk up to any Wii U, connect your 3DS, and start playing from your last save.
But anything to reward gamers for having both the 3DS and a Wii U.
3. Majora's Mask Wii U.
I've had this idea for how to remake Majora's Mask (although really, it's an entirely different game.) Kafei is Link's permanent partner through the whole game, allowing for local multiplayer. Kafei talks, Link continues to usually remain silent. Items and weapons have to be shared across two characters, acting as an on-the-fly class function, and you have to use the gamepad to throw or catch items from the other player if you need to swap items during battle.
Topped off with photorealistic graphics and an even darker script aimed at getting a T ESRB rating.
