New York City has thrived as an "entertainment capital" of sorts for the last two decades, and this actually provides incentives for major corporations to maintain offices there even if they move their headquarters and operations elsewhere. Someone in a major U.S. corporation told me that this remains the case simply because so many of their top executives (including ones from foreign offices) attach a certain status to hosting meetings and events in New York City.
Heck, I think even NASCAR has an office in Midtown Manhattan.
Look at Charlotte.
Or countries.
The office towers going up on the Jersey side of the Hudson should be a huge clue-by-four to the City leadership wrangling and wangling and letting Moslems interfere in redevelopment of the World Trade Center, that they'd better get off their butts and do something about their situation.
Nobody wanted to rebuild the WTC towers because they supposedly had so many occupancy problems in the first place, but the people saying that stuff, can't explain why New York firms are building high-rise office space over in Jersey.