“The condo market that helped propel the change has begun to cool in many American downtowns. But the shift in skyscraper architecture from commercial to residential has been so sharp and widespread that it’s difficult not to think of Norman Foster and David Childs as an anachronistic pair: as, say, a couple of contemporary composers who have produced dueling string quartets or two television network executives deciding to launch competing half-hour, laugh-track sitcoms that also happen to be very well-made.”