When we think about which teams are successful in terms of attendance and community support there seems to be a stark contrast between those at the top of the list and those at the bottom in terms of actual market size.
What if the solution to getting increased engagement out of Toronto is to pattern it more like those who are successful. Community, the small market teams tend to have the largest draws mostly because of community pride and a sense of ownership (in same cases literally). But London (UK) isn't limited to couple of teams in Premier League, the city may have as many as 4 or more teams at one time playing top flight.
What if what Toronto needs is actually more teams, just one for each of its major neighborhoods. Create localized teams that will focus on carving up 6 million ish people in more manageable chunks. Where the local community gets to feel the team is theirs because its in their back yard with their name on it.
Cross town rivalries would boost interest in each team, also if Toronto had four teams then that is 3 to 4 nights a week with a Toronto area team playing, think about those media rights. Stagger their schedules for bye weeks and there is never a week the entire season where there isn't at least one game being played somewhere in the city.
Even if the other three teams each only draw as much as the Argos that's an additional 45 thousand paying butts in seats on average per week. In time as loyalty grew and team outreach efforts targeting their local communities to get kids and others invested the attendance would grow for each.
Maybe the path to making Toronto a bigger draw is to make its focus smaller?