I think they should just forget a separate console.
Just make an SCD dock for those who are willing to pay extra and let that be that. They can release that quietly lets say for fall 2017.
The appeal of the NX currently is that there isn't really any kind of device like it on the market and the portability is a big part of that, they need to emphasize that, having a separate console model will just muddy that message and down play the appeal of one machine that can do everything.
Besides every Nintendo portable has outsold every Nintendo console of the last 20 years by a huge margin. Even the DS outsold the Wii, likely all that would happen is the portable NX that plays basically all the same games would crush a console NX's sales. Imagine the 3DS had passable/playable versions of Mario Kart 7 and Splatoon, the Wii U might not even have sold 10 million.
It's just not worth it, focus everything on your one model, the portability instantly makes it unique versus a PS4/XBox.
