IndyCar races on Ovals, Road Courses and Street Courses and streets contain manholes, catchbasins, curbs, streetlights and other municipal plant, both above and below ground. In Toronto even the trees along the main the start line are in planters and are removed every year for the running of the Honda Indy. If they want to make it pretty they could always coat the road with some new tar but this is no reason to move the race out of Toronto.
The bridge is still standing
It takes a lot of steel and concrete to setup the Honda Indy Toronto