The October 2016 Douglas Elliman Real Estate Guide for Manhattan reveals some fairly startling hints about the “health” of NYC real estate. For months we’ve been writing about the soaring capacity of luxury apartment buildings in New York City and it looks as though that capacity influx is starting to take a toll as the percentage of rental inventory offering landlord concessions soared to 23.9% in October, more than double the 10.4% recorded last October.