Ontario overall benefits from the pole shift in that it will arrive at a warmer climate, will have ocean access from the Hudson Bay and what will become the St. Lawrence Bay, and will be a land bridge supporting travel between the lands to what is now the west and east. Ontario has land to the north that is of a low enough elevation to be swallowed by the melting poles. This will consume a good half of Ontario, but will bring the Hudson Bay closer to survivors huddled in the highlands. Fishing will be good in the oceans after the shift, as the high level of carbon dioxide will make the oceans lush with vegetation, and sea food will follow in becoming abundant. As a land bridge, Ontario might find itself with barter and communication opportunities, also.
Note Great Lakes commentary.
Note East Coast Migration commentary.