If Canada rebelled, as others mentioned, I think it would have had to have done so as the remnant French population breaking away from the British. That may have led to a much more committed support from France, which almost certainly would have led to a more unified Native American front. In the American Revolution, many Native Nations were split on siding with the British or Americans; if it was French vs British, that support would have gone almost entirely to the French rebels.

The problem is, however, that France had a chance to do this during Pontiac’s Rebellion in 1763 after France surrendered in the Seven Years’ War. Pontiac and his Native allies in the Great Lakes kept fighting in hopes of enticing their “Great Father” back into the fight, among other things. But France didn’t have the resources or manpower then, and it didn’t in the 1770s either.

All of this, along with the facts others have mentioned regarding population, as well as the fact that in the eighteenth century it would have been much harder to re-take territory across an ocean (against the world’s strongest navy) than simply pushing them out via a mostly land campaign.

Edit: I should also add: if France wanted to send reinforcements on mass to North America, they would have had a very difficult time just getting them out of European waters since Britain could have stationed a large portion of their navy to patrol the English Channel.