Yes, that can work. I think that it's a matter of setting an example. If you believe in it and manage a team, the message will get through. Again, the example must be set at the highest levels.
I'll share a personal anecdote. When I was a student, I did internships. I was offered an internship at the Department of Finance, here in Ottawa. I had the choice between this internship in Ottawa and an internship at Hydro‑Québec. I chose Hydro‑Québec because I was told that, in Ottawa, on Wednesday mornings, people spoke French in the department. I figured this meant that, for the rest of the week, they spoke only in English. The Hydro‑Québec internship was in Rouyn‑Noranda, not in Quebec City or Montreal. The bottom line is that, for relatively similar positions, the language aspect came into play. I didn't realize this at the time.
You can have activities to promote French. However, if you don't believe in them and you're simply doing them out of obligation, it won't work. The key is not to be a francophone, but rather a francophile.