Seeing how Sony is introducing the Vita TV which allows some Vita games to be played on the TV, I've had this idea of how Nintendo could cash in on 3DS games on the Wii U.
The "Super 3DS" is a throwback to the Super Game Boy on the SNES for young 'uns who don't get the reference, or the GBA Player for the GameCube:

But my idea is pretty different from the above, as we've come a long way with wireless tech that requring extra hardware IMO is uneccessary (besides, the hardware Nintendo needs to sell more is the Wii U anyway):
- You have a Wii U and 3DS
- Lets say you buy a 3DS game, like Luigi's Mansion 2.
- On the Wii U you have the option of downloading a "Home Play" version of Luigi's Mansion 2 for Wii U for $10 more (lets say). What does that do? Well in addition to being able to play Luigi's Mansion 2 on your 3DS on the go, you can now play it on your Wii U at home as well ... in 1080p HD with Wii U tablet/Wiimote controls (if the developer wishes to add more control options).
It's an easy way for devs to squeeze more money out of their 3DS games by simply offering an upscaled version that the Wii U shouldn't have much trouble running (Nintendo would probably have to create an all purpose 3DS emulator for the Wii U). And it gives the Wii U a lot more games to play.
To prevent Wii U owners from just buying the 3DS cartridge and not having a 3DS system, Nintendo could mandate that your 3DS/2DS system must be in range of your Wii U for "Home Play" to work. And of course you could play your game at home and seamlessly transfer your save data to your 3DS so you could continue to play on the road.









