And even in the event of the allies making a total mess of things France 1917 is not France 1940. The French would fight to the knife, and keep on fighting from their colonies if necessary. Clemenceau is the Churchill of WW1.
"Fighting to the knife" didn't really help the Germans to win against the USSR in 1944.-1945.
And really, "keep on fighting from the colonies"? That would mean that the French have lost the metropole, and with it the entirety of their war industry and a huge chunk of its recruitable population, and all that after suffering 3+ years of death and devastation, all of which was ultimately for nothing if I might add.
Forget about the "all-conquering German supermen", the Entente here are displaying such a degree of stuborness that would have made Dwarves proud.