Even if you somehow navigate the impossibility of getting a Wii - even a virtual one - to draw two screens, you would still need to emulate a GBA on the Wii U at the same time as maintaining Wii backwards compatibility.That is probably far less likely to be possible, but I wouldn't oppose such implementation if it could happen either. Still only one Gamepad can connect to the Wii U as things stand (though it was supposedly going to be capable of connecting to a second game pad), so for games like 4 Swords Adventures and Crystal Chronicles, getting DS/3DS connectivity would be ideal to get the multiplayer experience operational on a Wii U. And that would almost certainly require another CPU core.
You also have to keep in mind, Nintendont is running from the vWii side of the Wii U, it is for all intents and purposes Wii homebrew that runs on Wii U as well. And while sure, we've been able to mirror the main screen and use the Gamepad as if it's recognized as a Wii Pro controller or Gamecube controller, no Wii homebrew has been able to send a separate display to the Gamepad, and I really doubt that it even possibly can be done.
The idea of letting a DS family system emulate a GBA linkup is at least theoretically feasible though - but keep in mind that Nintendont doesn't actually support GBA linkups at all right now - you need to enable Native Controls, which passes the Wii's GCN ports to Nintendo's official driver code.
Last edited by N7Kopper,