What I can say is that from a statistical standpoint, the biggest problem is that once most of these students are out of the school system and in the labour market, they don't get much of an opportunity to use their second language. Their proficiency declines as time goes by.
Promoting opportunities to use the language, by instilling a greater appreciation of French and the importance of French to Canada, for example, could certainly contribute to the solution. It's important to see more than just a symbol. It's obvious that people need opportunities to speak French.