I don't think this is a case of DL competing with KL. Besides, even if it was "competing" the extension of the JV to include DL, KL, and AF would render that moot. KL would make as much money from DL flying the plane as they would if they operated the plane.

The NW/KL model was about leveraging the AMS hub to increase the number of ex-US gateways. By my count, it looks like the NW/KL JV served around 15 destinations ex-US. What NW/KL were able to do with this model was to maximize the number of single-stop destinations in Europe for the 15 or so major markets they operated in. With this model, someone in BOS or LAX could get to even smaller EU cities in as little time as possible. Similarly, someone in a smaller EU city had good access to most of the top US markets. For good measure, the JV certainly captured a large share of the AMS O/D market.

What the NW/KL JV was weak at, though, was maximizing the single-stop options between smaller US cities and even many major EU cities. It took 2 stops, for example, to get between PHX and MAD with NW/KL. I also suspect that the NW/KL JV captured a relatively small share of non-AMS traffic ex-NYC, with the proliferation of non-stops from either JFK or EWR. I suspect that the strategy with the new JV is to use ATL, especially, to fill the first gap: one-stop access from smaller US cities to major EU markets. I think that JFK will be used to fill that first gap, but more importantly, will be focused on capturing a larger chunk of the NYC O/D traffic to the major EU markets.

FWIW, you are starting to see them slap the KL codes on a lot of DL routes. For example, you can fly CPH-ATL-MSP under a KL code.