Up north:
-Acadia surviving would help, particularly averting the Great Upheaval, so you have Francophones actually still left in *Nova Scotia. France needs to somehow recapture it in the Seven Years' War, recapture it in King George's War, or better yet avoid it being captured at all.
-Having Fort Beausejour be defended in the Seven Years' War saves *New Brunswick and PEI.
-Have France somehow capture and retain Newfoundland/Terre-Neuve, so the Francophones of Placentia/Plaisance aren't forced to relocate to Cape Breton to found Louisbourg.
-France somehow taking over Rupert's Land if not for actual population purposes, then at least for securing the Great Plains for their network of forts in Canada's prairie provinces.
In the west:
-Fort Duquesne, Carillon, and Niagara somehow survive.
-Fort Toulouse defended somehow.
It's rough for France to keep all its land in Louisiana and the American Old Northwest/Southwest. Your best bet is to have them focus on what would be the future Canada - save Acadia and Terre-Neuve, snag Rupert's Land, and defend *Ontario west to *Alberta!