Just because international diplomacy uses english does not mean out languages are dying out ffs.

You as a frenchman I thought would be particularly concerned

Why is that? Should I disappear if French language was to disappear? Am I legally bond to speak only French or to keep my mouth shut?

I love French. It's one of the nicest language I can think of but I speak four languages and I can ask my way around in a few others. So, I would not worry too much about my ability to communicate with people if my dear French language was to suddenly vanish... but why and where would it so suddenly vanish? Maybe in the vast emptiness of our soulless age? It could be that. It's such a sad age, so ill suited for a joyful language like French.

More seriously, France is certainly not the superpower it once was, we can all agree on that (some will agree a lot more happily than other, I know that) but French is something like the 6th or 7th most spoken language on the planet if I recall well (which I may not). And even though it's hard to date the apparition of a language, French has been officially around for more than 1100 years and the last time I checked on its label, the expiration date was not anytime soon.

Lastly, don't forget the most essential point: we French have this unique way of speaking English that makes us so charming. So, yeah, I would not worry too much about French going away.

I don’t understand this enormous metaphor

The size of the metaphor one may step in mostly depends the dog. And the carelessness of its owner.
Some people should really care more about their dog and their metaphors.