Based on every factor I can think of, it really comes down the features of the system, that no other system has, that they are trying to showcase. Not just for consumers, but I also think its meant to be an example for outside developers. The innovative tool of the console tends to be the selling point, outside of a couple of systems/handhelds perhaps.
Including the earlier example you mentioned, I would say that Nintendo Land was supposed to be that staple for the Wii U at the time.
If the NX is a fusion deal like what is widely hypothesized, I'd imagine it'd be a full game on the console where you can use the handheld, but then you can leave the console and the handheld will have a point generating system similar if not the same as, the walking coin system. Unsure if direct gameplay will affect mobile, or rather I may just prefer not to think about it
I was gonna answer this last night but, I was soo tired I fell asleep
