The Bills playing in Toronto was more about politics than it was anything else. Prior to the sale of the franchise, the there were a lot of rumors that the Bills might be on the move some day, and with a large part of the fan base being from Canada, Toronto seemed to be a viable option if not for the presence of the CFL, of which the league has had a reluctance to disturb. Playing a home game in Toronto was a poke in the butt to some of the pols in upper New York State.
I'm all for playing preseason games in locations with suitable facilities outside the Seattle metro area, such as Portland, Eugene, or Vancouver. The first NFL game I ever watched was in the early 70's when the Niners played the Broncos in Spokane in what was then called an exhibition game and was back in the days when they had 6 preseason games. But I doubt that they'll even do that as they can make more money in their own stadium and the team wouldn't have to travel.