Something to the side of the current discussion. I wanted to go back to something Nirolak had noted about 3DS software a few months back when we were entertaining the ideas of the NX being winter and MH:Stories being on it. And that has to do with how many games on the system, despite their art-styles such as BDefault and others, are usually able to be rendered at higher resolutions and still look quite nice, thanks to the art style.
The example back then was BDefault images rendered at higher resolutions, and the now-coming MHStories looks perfectly fine rendered at higher resolutions as well. Nintendo own games probably would also not be all that bothered by rendering at two different resolutions for cross-gen games though I'd expect Nintendo to push more towards NX to build the audience.
I bring this up because of the rumor on 3DS support in 2018 which, while for the west can be done purely on localizations for two years, is not so valid in Japan. But then I wondered, would Nintendo take a page out of the "ecosystem book" and leverage the 3DS's rather large population along with the NX in a bid to get a lot of 3DS/NX support. If the latter is built well/correctly, porting of 3DS titles could/would be rather simple and it allows Nintendo to not be forced to "start over" with the NX while also feeding themselves and the market as a whole with continued 3DS support.
For instance, the rumored Pokemon game... while weird to be a pure NX-only follow-up, sure wouldn't be nearly as weird as an 3DS/NX title in late 2017.
I could see them even push this aggressively if they want to take control of the market.