With Chicago's super-tall ego, and inferiority complex, don't be surprised to see some of these visionary projects come back to life, in some form or another.
Do you think, for one solitary minute, Chicago is going to take that sitting down, another city in this country building the tallest, when they've had that honor for so long?
Knowing proud windy-citians, it wouldn't surprise me if they voted in an additional sales tax, embraced by all, to finally finish Calatrava's Spire, and use it as an observation lookout, until the units slowly get leased/sold, little by little!
The rest of the country can give the FAA a round of applause for scaling back the proposed 2000 ft tall Stratosphere Tower, here in Las Vegas, back in the 90's, down to 1149 feet! If that had been built, the Spire in Chicago would have been built by now, at 2250 feet!