I don't know if The Grey Warden has settled on the events of the French uprising, but I'd like to add a few things:
-French university and indeed high school student numbers didn't balloon before the 50s in real life. So in the 20's you'd have at most a few tens of thousands of university students in Paris, mostly bourgeois upper-class. Of course you'd have quite a sizeable artistic and political avant-garde, but they could never muster the support of the majority of students. What I want to say is that a student uprising in the 20's is impossible.
-Under the 3rd Republic, the head of the government was the President of the Council, much like in Italy today, the President of the Republic being only a figurehead.
-Television didn't exist, or at least was extremely rare in the 20's/30's.
-The army is a staunchly conservative force (like in most places), and would support the government. In 1870, when the Commune took over Paris, the government retreated to Versailles and then proceeded to lay siege to Paris.
-In that regard, the rest of France, much less prone to revolution than the capital, would certainly be quite resistant to a complete regime change.
-Since the Haussmanian reconstruction of Paris in the late 19th century, the city has been crisscrossed by wide, open avenues which are simply too wide to be barricaded. Thus the police would always have access to most sections of the city unharmed, leaving only a few neighbourhoods whose streets had been untouched, namely the Quartier latin, really off-limits in the event of an uprising there.
-In the early 20th century, the main French political party was the Parti Radical de Gauche, a very moderate center-left party representing the progressive middle class, the bar-owners, the small shop owners, etc. It favored social reforms, but was violently anti-revolutionary.
-In the event of snap elections following social strife, expect the right to gather the support of the law-and-order middle class across the country.
-By the early 20th century, the bulk of the Parisian working class actually lived outside of the city proper, in the "banlieues rouges", the ring of suburbs outside the city limits.
-The SFIO (Socialist Party) was a pretty moderate governing party. The leaders were marxist, but by the early 20th century didn't really believe in Revolution anymore. In the event of an uprising spearheaded by the PCF (Communist Party), it might furthermore be wary of the PCF gaining dominance.
-The PCF had the support of around 10-15% of the electorate, and was widely shunned by the rest of the political spectrum (that was in part due to its perception as a foreign force under the command of the USSR, which it obviously wouldn't have in PoW)
-Arguably, the most significant threat to the French Republic in the 30's was actually rightwing antiparliamentary, proto-fascist militias, the Ligues, made up in large part of former soldiers fed up with the incompetence of the government. It's possible that due to the duration of the war, nationalistic, violently xenophobic forces might have gained in popularity. In that case, however, expect an extremely strong reaction from the Left, which, bar the PCF, was very attached to the parliamentary republican form of government. The PCF, on the other hand, would be the ideological polar opposite of the Right, so it would be even more opposed to it than other leftwing parties. A civil war, rather than a revolution, would actually be more plausible.
@Dinh AaronMK In France, the colonial question actually cut across party lines. Members of some leftwing parties supported it, as in their opinion colonization brought civilization to the natives, and members of rightwing parties opposed it as they thought it lead to negligence of the development of France itself, as well as focusing the country's attention away from its fight with Germany, the "hereditary" enemy.