NYC will always be junior.... there simply isn't much compelling there to make it otherwise for Delta at least (I'm from NY, no offense). Difficult commute, cover 3 airports, extremely high cost of living, "junior airplanes", etc... ATL 717 is still considered preferable to NYC 737/AB for the most part barring locals. From what I've heard LGA has the closest deadline with RNAV 13 approaches being the restricting factor. Apparently JFK will have similar restrictions sometimes later than that. Let's see what happens in the next couple of years as the C-series comes online vs the 717.

NYC will continue to be a base in the meantime with slight shifts in start points between LGA/JFK/EWR until the FMS/GPS mods are done on the -88/-90.