A sad state of affairs if DTV got a NYC link before NCL. If I was an airline I would be very dubious of starting such a route from a fairly small airport with a smaller catchment area than NCL. NCL also has a better route structure, with potentially other loco routes used to connect with a loco US link. NCL has been crying out for so many years for a link to the US, but I do think that CO or similar would be more viable in terms of offering onward connections.
It seems that route expansion has gone awfully quiet at NCL of late. Either there is no more scope for growth and hence airlines are looking elsewhere or the airport management have an ace up their sleeve and we'll see another big expolsion in new routes happening soon. Lets hope it is the latter as NCL is the only UK major airport now without a link to NYC, with BRS and BFS etc already having one. It also seems that airports such as LBA, BRS are attracting new airlines and routes more frequently?
Maybe NCL has reached its capacity, lets face it at nights most parking stands are occupied and the departures area of the terminal is sometimes overcrowded and maybe airlines do not want to operate at off peak times.