So much 20th century stuff...
Something 19th century then. At the end of Napoleon, Talleryand convinced everybody that a strong French Kingdom was in their best interest. After all, the French Kings were just as much victims of Revolutionary France as everyone else, and a strong French Kingdom was needed to prevent a repeat of the situation! Thus, France was kept as a Great Power.
So... what if the Coalition allied decide that the safest way to prevent a repeat of the situation is to de-power France? Alsace, Lorraine, Belgium, maybe even the Franche-Comte become some way or another part of the German Confederation (as annexation by German states, or as newly carved out states), the French central state is weakened by the re-establishment of apanages and feudal fiefs (Brittany, Orleans, Auvergne...), etc. Thus France at the very least will take some decades to reestablish itself as Great Power. How would that 19th century look like?