Allow me to write notes on the maps using the Gamepad, even the area maps, so I can track quests and solve dungeons. Maybe charge for bottles of "magic ink" to keep LoZ's trademark difficulty and immersion (rupees, not DLC)
They should add a second form for the final battle. That would be a real treat for WW vets.
User-made, decorative islands that people can create, download, and rate.