Curves? Well to put the bridge where the original poster placed it, you may have to arc it away from Weston on the approach or go via the car dealership if you wanted a straight run to Dixon.
http://www.bing.com/maps/?v=2&cp=r8...32763&dir=0.889091543128022&sty=b&form=LMLTCC
Are you speaking of the southern connection to Eglinton? That would be arced under the Kodak lands.
Ridership? Please. Surely you don't mean to/from the airport. If there is no ridership then why is there a GO station at Weston and Lawrence? Are these buildings empty?
http://maps.google.ca/?ll=43.695967,-79.552742&spn=0.00626,0.009431&t=h&z=17
Cost? I would submit that building this bridge would be less than building one across the 401. The approach at the airport itself would be cheaper. Turning north at the Kodak lands would avoid building through Mt Dennis. Connecting to GO at Lawrence would save the cost of a new connection at Eglinton. The Richmond expressway land could still be used to bring Mississauga BRT to the LRT (Weston/Jane) rather than vice versa.