I wouldn't worry too much. They will negotiate. Still the nerve of the FAA to say such blasphemy!
I'm surprised Skyrise didn't get a height reduction. I think its safe to say that if we do get a height cut on this, it will be in the range of 700-800 feet. I hope I'm wrong on this btw, but its probably the reasonable option given the thick-headedness over there.
We still have many towers going up, but stuff like this only hurts the city. Thats a lot of good office space they will lose with such stringent requirements. This is still something like 2 years from construction if the timetable goes smoothly, so a lot may change by then.