The People in Louisiana were always french; they were just in denialNorthern Italy has been smashed consistently over and over again by the French. They are getting annexed because the French government has and is going to dedicate a lot of men and resources to properly integrating that part of their conquests.
Louisiana should actually be easier to take then Italian lands. The last war really annihilated their fighting adult population, while the war itself probably did a number on the civilians. This would be followed by the ton of French settlers that are to follow, pushing out the natives. All in all, the demographics looks to heavily favor the French.
I think I remember France not caring much about Africa.