In addition to the supertalls RW mentioned, there will be several more in the Far West Sude such as Sherwood Equities' 34th &10th, Extell's WPC site and 33rd & 10th (has the potential to be truly massive), and these are only a few of the commercial properties with over 1,000,000 sf of air rights in that area.
Several more supertalls in the area of the proposed midtown rezoning such as 425 Park and 237 Park will become possible should the mayor's plans for this area go through, which seems very likely considering it is being fast tracked. Then there is the approaching redevelopment of the Javits site which will probably yield the tallest skyscrapers in the city and maybe even #fingers crossed# New York's, or even America's first hypertall.
It's going to be a very busy decade to say the least.