NOA is keeping the New 3DS off shelves to sell the dated original 3DS model instead? That's idiotic. Just discontinue the old inferior model.
Existing inventory doesn't suddenly disappear just because a new model is released. There's bound to be some overlap and retailers, that collectively balked at carrying SKUs for different colors, probably don't want five variations of essentially the same product for any duration of time. It makes sense to sell New 3DS XL because the XL models tend to sell better. The standard New 3DS also has those faceplates. Do retailers want to carry those along with all the other 3DS stuff?
And keep in mind, Nintendo already did something like this six ago, and DSi wasn't a resounding success. It was just "another DS" stores carried so I can definitely see retailer pressure having a hand in this decision. If Nintendo of America was put in the awkward position of taking back all the standard 3DS models to make room for the standard New 3DS, I can't blame it for thinking, "Well, F that. Let's clear inventory then we'll think about releasing the new one here."
Right now NOA should not be manufacturing any old 3DS's (except maybe the 2DS) and sending them to stores. It should be the New 3DS or nothing. All old models should just be the pre-existing store stock getting cleared out.
Well, that isn't really Nintendo of America's call since it doesn't manufacture hardware. The original 3DS models may (and probably will) get discontinued later this year, but I'm not sure what the rush is. Nintendo of America would be replacing the model that sells less than the XL model with a different model that sells less than the XL model. It's less of a priority.