Granted, there is a nuisance factor of having all those international flights flying over your head, but we are talking money out of nowhere. Canada should get in on this and capitalize on its northern position and gigantic landmass.
-Remove tourist visa requirements for anybody with a valid American or European visa within the next or previous 30 days.
-Remove tourist visa requirements for citizens of rich Arab countries like the UAE and Saudi Arabia.
-Remove tourist visa requirements for citizens of Caribbean countries.
-Remove tourist visa requirements for citizens with fewer than 10 million people.
Obviously, some civil servants would loose their jobs as a result of this, but they could be reassigned to immigration enforcement.
Removing visa requirements doesn't mean letting every Haitian with a one way ticket just walk out of Pierre Trudeau airport, immigration officials would still have to right to refuse entry of those "tourists" who clearly intend on working here.
The government should also close Pierre Trudeau in Montreal and make Mirabel that region's airport. Mirabel does have some design issues ( tarmac buses to and from planes) but it can accommodate more planes, and, most importantly, do so without a curfew. Ideally, Toronto's Pearson wouldn't have a curfew either, but alot of people live in the flight path...
A tourist who is allowed to fly over Canada en-route to the USA should be allowed to land in Toronto and enter the USA at Niagara Falls without bureaucratic hurdle. Niagara's kitsch industry would be greatfull.