Three big things on my list:
1. Fix up the online system, get rid of friend codes.
2. Provide USB support for headsets and flash drives. Not going to buy an SD card JUST for one console.
3. Star fox and F-zero.
I'd tell them to localize all of their old Fire Emblem games on a collection for the DS. Maybe work on another Star Fox game.
Seriously, the Wii and DS pretty much slimmed their big hitters down to Mario, Zelda, and Metroid due to narrowing marketing focus and development focus.
Bloody kids only know Marth and Ike from Smashbros.