I entirely agree. I would add perhaps that this often comes as a cold shower, but that's not necessary. Proceeding gradually is a good idea. At the campus, a lot of francophone students from Quebec eventually want to study in English at the University of Alberta. So they proceed gradually by taking a few courses in French with us, and courses in English.
Conversely, our anglophone students learn French there. They also proceed gradually. They have access to the residence, where they only speak French. Whatever the case may be, this will never replace a trip or complete immersion in a francophone environment.