They’re no longer colonies—they’re integral parts of France, in the same way that Hawaii is part of the U.S.

They have integrated them into metropolitan France. Like French Guiana in South America is legally part of France and all people born there are French citizens from birth. Also many of their former colonies are now smaller nations and considering France has a large well funded military they wouldn't stand a chance of leaving. Most French overseas territories that were left were small islands in the Atlantic and Pacific oceans like French Polynesia, New Caledonia, and Saint Martin. Also just like French Guiana many of these places are small islands or very small nations that are culturally and economically tied to France now from being colonies for centuries. French Guiana gets a lot of it's economic activity from the European Union's space agency being located there. So these small islandand nations have a strong economic incentive in being part of France and by proxy the European Union. Furthermore most of French Guiana's small populace is not of European decent most of the populace is acculturated former French colonial subjects from nations like Vietnam, Cambodia, etc. In nations like Vietnam Catholics are treated with contempt and suspicion because in the past they had sided in conflicts with the French colonial authority. So these former subject that had sided with colonial authorities seeks asylum in these areas of the former French Empire when they don't want to live in mainland France because of precised racial discrimination like Algerians have suffered there in the past or other reasons. But want to live in territory were they can use the French language, culture etc and still reap the benefits from their former service to the French.