adma
Superstar
I think if it had gone ahead (demolishing Old City Hall), we'd view it almost the way we view the loss of the old Registry building to be replaced by new City Hall. Some would look at old photos and bemoan the loss, but overall I think we'd just look at the whole development, including new City Hall, somewhat positively.
I somewhat doubt it in this case, because of (a) Old City Hall being a more significant landmark than the Registry Office, and (b) the SOM-style Eaton Centre being less significant than New City Hall. Maybe the margin decreases slightly re the TD Centre replacing Carrere & Hastings' Bank of Toronto--but not enough.
In fact, the best comparison point for the "somewhat positively" might be right here, i.e. Zeidler's high-tech Galleria, Michael Snow geese and all, replacing all that old Eaton's stuff and all that Yonge St frontage...