France, at least during the Ancien Regime, originally was a unification of several smaller duchies and kingdoms correct?
No, what you describe may fit the classical medieval structures, but it was no longer the case by the Late Middle Ages and onwards : an unified bureaucracy, political power was already present by the XIVth century, if challenged by great princes up to the XVth.
If something, Ancien Régime parachieved this bureaucratic and structural unifications (which shouldn't be confused with administrative centralization).
As for survival of ancient dynasties of Brittany, Aquitaine, and so, that simply doesn't makes any sense : almost all of these disappeared by the XIXth century either absorbated by Capetians (Brittany, Toulouse, Burgundy, etc.) or being chased off (Angevines, Armagnacs, etc.). You're assuming a sense of political identity somehow survived, but really, it didn't if it even existed.
At this point you had a strong common french identity that only went deeper with French Revolution, with everything about local ones were about folkloric customs. There was none, and I stress none, regionalist/autonomist/independentist movement worth of mention, if at all.
I think you're minsinformed about Communalist movement, furthermore. It really was not about Paris revolting, but a general urban dissatisfaction even before the war, and that was blostered by napoleonic defeat.
Before Paris revolted, as it was relatively passive in 1870, other cities did so (as Lyon) in order to proclaim a republic that, in current conceptions, was to be social.
Even in 1871, Paris wasn't the only communalist center, but accompanied by more short-lived (would it be only because governemental forces didn't left these cities, contrary to Paris) Communes as Marseilles, Le Creusot, Saint-Etienne, Narbonne, etc.
Something between "not at all" and "lolwat", I'd say.
