Beyond the great points you make about international engagement, a good friend of mine in Cameroon once pointed out to me that French has now become very practical, even necessary, as a lingua franca throughout the region. He told me he speaks two indigenous languages plus French, and without French he would still be unable to communicate effectively in some places within Cameroon, not to mention neighboring nation-states. Obviously, that doesn't mean that French must be the common language of the region, but because it already is, inertia is very strong.