Assuming every game would come to both the home-console and the handheld version of the NX, I'd say there's one important question then.
What would be more expensive? Solely producing generic large SD-style cards up to say 64GB that would work on both devices, or making both smaller SD-cards up to 16GB for the handheld and BR-based discs up to whatever GB for the home-console additionally.
In the first case, publishers only need to produce only one SKU of a game to be sold across a variety of NX-forms, reducing the need to manage supply for each version of hardware while the second case, would have the publisher make at least two sets of retail packages with all added disadvantages. Two sets of different plastic cases, two different storage mediums for one game with one maybe even needing to be given away for free if there's cross-buy (which seems logical with the NX-concept), said more complicated management of supply and not to be underestimated, larger storage capacity needed in warehouses and shelf-space in stores.
Of course, there is some math that needs to be done, but I think it might end up being cheaper to produce a single more expensive medium than produce two different seemingly cheaper ones. I don't think this is such a stupid idea.