I don't think 80,000 is that undoable. Cities like Milan, Barcelona, Dortmund and Dublin have stadiums of over 80,000 capacitities, and all of them have much smaller populations, in fact, there are more people living in the GTA than in Ireland. Of course the first three examples have world class football clubs and are situated in countries where football is the number one sport. In Ireland however, football is less popular, but they manage to get good use out of the stadium by using it for Gaelic Games, rugby, and football. In Toronto they could definately use the stadium for both American and "European" football (I don't like the idea of sharing it with a baseball team), and I also think that hosting a world cup would definately increase interest in soccer, possibly to the point where we could make good use of the stadium after the tournament was over. All in all though, when you look at the hosts for the biggest three tournament in the next six years (SA 2010, POL/UKR 2012, BRA 2014), Canada is already well ahead. While we would have to build 10 or so world class stadiums, we already have all the other infrastrucure (hotels, roads...) required for hosting the world cup, whereas the above hosts, not only have to build/completely renovate stadiums, but also have to spend millions (billions?) on other infrastucture.