I seriously don't think this has anything to do with NX. As someone pointed out here, this is most likely related to people needing to replace broken WiiU Game Pads.
However, it could also suggest that Nintendo are planning software and DLC capable of using two Game Pads. I can think of two announced (but not yet released) games that could benefit from that option.
1. Star Fox Zero
2. Project Giant Robot (which I still believe was a prototype engine for an unannounced "Punch U Out!")
I can also see a second Game Pad DLC for some already released games, such as Splatoon.
But most likely this has nothing to do with new software releases or various DLC releases.







