Not in the City proper, but Wonderland Road needs one final extension to Highway 3
https://www.google.ca/maps/@42.8108701,-81.2282703,15.49z
With all the traffic using the road south of the 401 now, it's one of the main connectors to St. Thomas. Just before Wonderland ends, it slows to 60km/h, curves to the E-W and you need to take another rural connector road to access Highway 3.
-----
In terms of Fantasy, if an interchange was added at Highway 3 and Wellington, then the St. Thomas Expressway could actually start at this new intersection with Wonderland. Heck this could be an interchange too. Properties aren't connected to Highway 3 until it's west of Wonderland.