Could France sustain a national redoubt?

Was the idea of a French national redoubt impossible?

A Breton redoubt was unrealistic, but continued resistance across the remaining French territory could have lasted because France still had reserves, supplies, and British reinforcement.

A defensible pocket confined to Brittany is dismissed as an impractical version of the idea. France as a whole, however, retained supplies, reserves, territory, and functioning ports through which British and imperial troops could arrive. Continued war would be destructive and costly for France. It would be worse for a German army already operating at the end of an overstretched logistical system.