If they realigned Dupont so that it ran in a more direct fashion between Dufferin and Emerson, would that not cause problems with the lands currently on the north side of Dupont, opposite the mall? The City can't simply deprive them of vehicular access to the street, without paying through the nose in injurious affection claims. It also can't force those landowners to buy the land that has opened up between their parcels and the realigned Dupont, and I don't think anyone imagines the landowners would be provided with free land.
I'm not particularly familiar with this redevelopment, and maybe these issues could be addressed, but it seems that a realigned Dupont would give rise to problems and expenses for very little return.