Nintendo doesn't make a penny off of Pokemon Go's sales. They got a flat fee for licensing the game for Niantic, but whether it succeeds or fails, it doesn't affect them.
Sounds like Nintendo is taking cues from knock off handheld clones by making a portable system you can plug in to your TV.
Does this mean the NX will more closely resemble a 3DS than a Wii or N64? I'd guess so, probably more like the NEO-GEO Gold system that came out a few years ago. If they aren't trying to compete with the big 2 (and lets face it, Nintendo hasn't competed with them graphic-wise in many years) then they are free to make this thing as small (or large) as they want.
I think Nintendo kicks much butt at making portable systems. They've dominated the market since there has been a market. Making a portable that can be hooked up to the TV is neat. I'm hoping the base is solid enough for stable controllers, and I hope those controllers are like Gamecube.