It won't and it shouldn't. The French will never, ever agree to anything that officially places their language on a lower level. They might accept de-facto lingua franca status for English, but they'll never sign anything that mandates it or recognises it. Discussing language is a recipe for pointless strife; the next step really should be taxation standards.
This said, the market is adjusting on its own. EU customers are voting with their wallets, and the more they move around, the more English-speaking cross-border businesses flourish.
France doesn't even recognize any other language than French within France, as far as I know. They have no minority languages, even though they have, and used to have, minorities.
> France doesn't even recognize any other language than French within France
Officially, France (and the Academy) only barely recognize the existence of French spoken in their former colonies, and even then only when it's convenient (to maximize the count of the number of French speakers). They go out of their way to try to "preserve" the French that is spoken by white French people in France itself as the only official version of French, so they sure as heck aren't going to recognize other languages spoken in France by minorities other than French.
My grandparents speak Breton too, though not with me. As children, they used to have their fingers smacked if they happened to say a word in Breton. Back then, the French of the Republic, one and indivisible, was to be heard in all schools and those who dared challenge this policy were humiliated with having to wear a clog around their necks or kneel down on a ruler under a sign that read: "It is forbidden to spit on the ground and speak Breton".[13] That's the reason why some older folks won't transmit the language to their children: it brings trouble upon yourself...
I don't want this discussion to turn something it shouldn't be. I'm talking about other European natives here, such as the Basques or Bretons, for example. So no colonies involved or other tricky subjects.
This said, the market is adjusting on its own. EU customers are voting with their wallets, and the more they move around, the more English-speaking cross-border businesses flourish.