Why would Air France be telling me (when doing manage booking / online check-in):
Vous pouvez reprogrammer votre vol AFxxx
Pour des raisons exceptionnelles, vous pouvez modifier votre vol sans frais supplémentaires, quelles que soient les conditions de votre billet initial. Si le prix de votre nouveau vol est plus élevé, vous devrez payer la différence tarifaire.
? Check-in is open, and the cabin I'm in isn't full (though I suppose it's possible some people haven't checked in yet), so I doesn't look to me as if it's overbooking. And if it were overbooking and so they were really desperate to transfer some people to another flight, wouldn't they be willing to absorb the loss if the fare on the new flight were nominally higher?