Nintendo could possibly be working on a catridge that would allow players to stream between their Nintendo 3DS and Wii U systems. French gaming site, Nintendo Master, site reports claim that the Cartridge would allow the 3DS to act as a secondary Wii U Game Pad, with the use of the Circle Pad Pro peripheral.
This news is partularly interesting due to the fact that several big games such as Super Smash Bros. 4 and Monster Hunter 3 Ultimate are arriving to both of the Nintendo consoles. Perhaps the release of this cartridge is in preparation for such games? Well, we don't know.
Nintendo has yet to confirm (or deny) these rumours, so for now we can only sit and hope.