I still think this is actually the NX handheld, at a push a handheld that doubles as a controller for the console.
It makes great sense if Nintendo also ships the handheld device with the dev kit for the console - some of the
big sticking points about NX are
it's
1) firstly a platform that encompasses several distinct devices but with a shared software and hardware architecture
and
2) secondly a platform that'll capitalise on making digital downloads across two separate devices "cross-buy" due to developers' ease of targeting several devices under a unified development environment
So it
makes great sense that Nintendo would ship both form factors out to developers from day one, to ensure that developers are targeting either both handheld and console for their games, or one or the other, or at least thinking about how their games might scale between the two.
It could be all for nothing if Nintendo introduces one later on in the cycle - unlike Apple they can't guarantee that developers will quickly adapt their apps to a new device (like how iPad quickly received developer attention and apps that specifically made use of the extra real estate of the display).