My point about EZY was that the NCL and BRS bases were at one point very similar in size and types of routes but have gone in different directions - BRS has expanded considerably and NCL has contracted and focused on sun routes. Why? look at the relative economic indicators of the two regions - it's as simple as that. Fewer people with the disposable income to spend on air travel and then the laws of supply and demand kick.
The North East is a small, relatively poor market. NCL does well in the circumstances, particularly in connecting the region to the hubs and the rest of the world.
Most of the foreign carriers have gone as the based carriers have expanded - e.g. Thomas Cook would have been at one time two TCX with some foreign operators and is now two TCX and a smaller leased in a/c. Look at the TOM Verona over the last couple of years - used to be TOM a/c but another use is found for that and so it's been operated from the other end instead. They might come back as the based airlines expand and find themselves needing more flights but not enough to justify another based unit