A Cambridge - Brantford highway could be useful too, but a super two connecting from the 8/401 interchange to Wayne Gretzky Parkway in Brantford would probably be more than enough. Maybe make plans for it to eventually be upgraded to a 400 series highway.
another little pet project I'd like to see for personal reasons is to see the Caledonia Bypass connected with 6N around the Hamilton Airport and see the long ago planned Highway 6 upgrade to at least past Hagersville. The slog down to Lake Erie on Highway 6 could be a whole lot quicker with those upgrades.