DS Games on Wii U

I was told once that Nintendo may be coming out with an attachment for the Wii U Game Pad to allow it to play the DS games from it.

I'd like to know if any of this is true. If so is there any other system's games that will be able to be played the same way.

I'm not a fan of Hand Held game Systems anymore. I'd like to be able to play all the Gameboy - GameBoy 3DS games on a console. I'd prefer to not have to purchase them again in the Virtual Games since I still have my original gameboy and the Super Gameboy.

So without the use of Virtual Console, can any of the previous system's games be able to be played on the Wii U besides the Wii Games?