Since it was somewhat revealed through the Wall Street Journal and somewhat speculated for while, my thoughts are that the NX is a home console and a portable, but Nintendo will need to have separate and bundled options to sell the idea
For the "NX Home" and "NX Portable" they will probably have 3 different options:
NX Portable SKU $199,
NX Console SKU (with a controller without a screen if necessary) for $299.
NX Ultimate at $450-$499, bundling both devices together on package for a possibly lowered price than buy separately.
Also, Nintendo is most likely giving the NX more power than their previous two consoles due to developers directly saying they would not release ports on Wii U due not only to sales, but due to the difficulty with the system being able to run ports from PS4 and Xbox One easily, porting to the Wii U became not worth it basically. Ease of porting to the NX is probably one of the big reasons for boosting the specs, the other reason is to the give the NX a longer life than the short lived Wii U, and make their fans very satisfied in the end.
Having the console also have the "take on the go" Handheld option can also bring in the over 50 million in 3DS user base, not to mention the controller innovations Nintendo can add and has hinted at in patents.