[left of center]

^ Definitely would have helped balance the South Loop skyline, and drawn the center of gravity of Chicago's downtown skyline a bit further south.

As for the old 830 S Michigan proposal, I wouldn't worry too much; Once 1000 S Michigan begins construction, the old YMCA parcel will be the very last lot left on Michigan. Really, the last developable lot fronting Grant Park once 2GP begins construction. A parcel that valuable will demand a premium development. I doubt any developer would waste an opportunity like that with a mediocre 600-700 footer. We will probably see a very nice proposal for it in the next market cycle.