I think one device that can be a home console and a portable is too tempting for Nintendo to pass up. They have been waiting 15 years for technology to get to this point and now its possible. Even the Wii U, I believe they wanted to make a portable console, but you couldn't put the chipset inside the controller then, now in 2016 ... it's possible.
From that main device they can probably birth other more specialized devices (ie: a console version that's anchored to the TV) but I think the main NX system will be something that lets you play games on the road and can beam them wirelessly to your home TV when at home. And there will be some other type of gimmick on top of that to encourage people to gather around the unit and play together some how.