I think in general dual screen is done for.
There hasn't been a dual screen game that did anything truly interesting in like ages now. Pretty much nothing for the entirety of the 3DS life cycle. The second screen invariably just ends up being a map display (or worse a HUD) that drains the 3DS' battery twice as fast.
That layout made sense for the mid 2000s when large touch screens were prohibitively expensive. But today it doesn't make any sense, by Nintendo's own admission, a single touch panel is cheaper these days. A single screen also provides generally a better experience for the player. It allows the main screen to have more real estate and that's a good thing as NX's graphics are likely going to be 360/PS3 caliber if not better.
You don't want visuals like that on some cramped little display.







