Also, what if the Italian fascists actually managed to recreate a New Roman Empire ?
I saw many scenarios in which Italy played her cards well during WWII, and for example, remained neutral in the main war but bought Tunisia, Syria, Lebanon (and sometimes Constantine area in Algeria) and Djibouti from Vichy France (and of course, Corsica, Nice and Savoy, but it's not the subject here).
Then, with Syria and Lebanon, Italy stages a coup in Iraq (with Rachid Ali or someone else), or even supports (alongside Germany) Rachid Ali, but covertly and while remaining neutral. The coup is a success, and UK can't declare war because Brits have too much on their plate. After the WWII, either Italy and its Arab clients (Syria, Lebanon, Iraq ? ) declare war on Israel, alongside Egypt and Jordan, so Italy also gains Palestine. Or Italy supports Israeli independence, but under the Lehi (Stern Group) which had some fascist leanings.
Then, either Italy entered war with Allies in 1944 and gained recognition of its conquests (if not from De Gaulle, at least from Roosevelt and -reluctantly- Churchill), or Italy just sat out. Then, at the end of the war, France was too tired to go to war against Italy alone, and UK and US weren't ready to support her (because war weariness + Soviet threat eastwards).
Then, and that's where I'm coming, wouldn't countries close to the New Roman Empire be reluctant to just become independent, with the Romans ready to gobble them (or at least, they'll think so) ? If Chad decides to separate from France, it will be too weak economically and military to resist Italian pressure.
Besides, France and UK would be more reluctant to let those precise countries go, while Italians might gobble them and their resources.
Also, what if the WWII played differently, and at the end, millions of German, Polish and other East European refugees go to the British Empire. Of course, those people flee poverty and Red Army.
The Soviets let them go, for whatever reason. And UK takes them in her African colonies. Which hadn't a heavy population (neither black nor white, even if blacks were majority of course). Those millions of European people could be a game changer.
Finally, with that different WWII, France is more tired. Perhaps France didn't capitulate in 1940, and fought constantly on its soil, and more of it was occupied. So, the French had to rely even more on colonial troops and workers, and had to displace industry to French Africa. And at the end, they need desperately resources from their empire, and are too tired to fight decolonization wars. Also, with WWI-like casualties, many European colonists in Algeria were conscripted and killed (many Muslims were too, but the smaller size of European community meant that they were really weakened). So less pressure against reform.
So, they create the Union Française like they did OTL. But instead of timid, half-baked, reforms like OTL, they do real reforms, because they know that France has no choice (France need resources of its colonies and cannot fight, so they have to give something in return basically). And colonized people too have some interest to remain in the Union (protection against outer threats and economic development), so they too will accept some concessions and to not have everything in one go.
PLUS, with the New Roman Empire, France don't want to abandon her colonies in general (because it means more troops and resources if there's another war with fascists -or Soviets-, which is not unlikely), and particularly don't want to let go colonies close to the NRE (because they don't want the NRE getting the oil/copper/whatever in Chad/Algeria/Niger, and because if there's a war with Italy, they want bases to attack Libya).
Which is another reason to make real efforts to keep colonies, instead of reluctantly giving some little things when pressed.