The reason ferry travel works to these regions is for two main types of traveller, and both involve thier cars:
1 - Booze cruisers looking to stock up on cheap wine to load thier car up with.
2 - Part-time property owners. People who live in France for a few months of the year will have alot of home goods to take or thier pets with them and like to have thier own car.
Therefore I would say it would be a stupid business move to base planned flight routes on this therory. Flybe announced a SOU to Cherbourg route a couple of years back. I dont think it even flew once (I may be wrong!).
The Northern France region would attract a small amount of commuters/business traffic and maybe the odd home owner looking for a quick trip over but i doubt you would see full loads.