It could be, yes. I believe the Nikkei report because they know their shit when it comes to the Nintendo, they got the 3DS XL, Nintendo making smartphone games, and even the report about Nintendo financing a Seaman game for 3DS was true (the creator confirmed it recently, the project just stalled in development).
So when they say they have info that says the NX will run Android apps I believe it. What I think it will be though is a Nintendo OS that can emulate/run Android apps easily and then Nintendo will offer the ones they want through their eShop and take a small licensing fee cut of the sales. And you'll have all your traditional Nintendo games there too in one place.
Though technically, a tablet is a "handheld" ... I mean what else do you hold a tablet with other than your hands? ;)
It would just be a slightly different form factor from today and maybe more similar to the Wii U tablet.
Or they might even do something crazy like make a frisbee shaped circular device. Who knows with Nintendo.
