There is talk that the Toronto Blue Jays plan to install grass inside the Rogers Centre (a dome). That would cause the Canadian Football League team they share the dome with (the Argonauts) to be evicted, because gridiron football is too destructive to natural grass surfaces that baseball teams need to play on.
So if the Argonauts get the boot, there is also talk that they might move to the Toronto FC stadium, BMO Field. That stadium would have to be renovated in order to accommodate a CFL-sized field. Once renovations come into play, why not put a roof on the place and presto, Toronto gets an intimate year-round football stadium.
True, there's already the Rogers Centre, but it seats 50,000 and is a lifeless tomb when half empty. It sucks for baseball, it sucks for football, it sucks for the other kind of football.