My old church is located under the old Citigroup Center skyscraper at 601 Lexington, which is also an entire block; Citigroup used to have both that building and the block across the street, 399 Park, for a couple of decades. When they moved out of those buildings to another neighborhood in Manhattan, that caused a drop in noon mass attendance but that was really about it. Their presence didn't destroy the neighborhood, let alone the city, and their move didn't destroy it either.
The fact that NYC is capable of handling Citigroup-sized companies and Google-sized companies moving in and barely even noticing is one of the deep reasons I like living in NYC. I wish more other cities would do the same, because I don't think there's anything unique to NYC about the ability to do this. Maybe population - although the Denver-Aurora-Bolder metropolitan area, at 3M, isn't that much smaller than NYC (8.5M). The internet is telling me the Google Boulder office can support up to 1,500 employees. You shouldn't give them corporate welfare, but also you should just be able to accommodate them without that, they're not that big. It should just be a building, and you should have lots of those.