The way Reggie, Tanabe and now this Unseen 64 guy have spoken about NX, they speak of it in singular terms.
So that's why I'm kinda hedging on the multiple SKUs thing. If there's not going to be a big difference between the handheld and home variant in power, then you may as well just let the handheld stream games to the TV.
Maybe the portable + home nature of the device is integral to the gimmick/novelty too. IE: say you can pick the NX up and take it into the kitchen table and set it up so that the family can play there somehow. If it has a screen on it you can play in any room and maybe there's some novelty to it design to bring people/family together in any room. Sounds Nintendo-like enough. Stuff like that.