I would not be the slightest bit surprised if Apple placed a detonator in every iPhone sold in France that would explode internally; effectively rendering the iPhone useless if the iPhone goes beyond a 1000 mile radius of the Eiffel tower.
Point taken, I think the catch would be that the phone will be really expensive like 800 euros or that the whole user interface and language would be in French. I'm sure you will be able to use it outside France as that would defeat the purpose of roaming.