My answer is twofold.
I recently read two studies on the economic advantages for Canada and New Brunswick in terms of bilingual nature, in terms of increased trade with francophone countries, and for New Brunswick in terms of the degree to which its ability to offer services in both languages has resulted in major economic advances measured not in millions but in billions. Not only for those who are bilingual, but also for those who are unilingual, it has become a service centre for call centres. That is because they have a bilingual workforce in which they have a sufficient number of bilingual employees who can do service calls in French, but also they hire unilingual English employees who serve the English clientele.
In terms of knowledge of other languages, other than Canada's two official languages, one of the things that I have observed is that knowledge of the other official language is often a stepping stone to learning third languages. Speaking anecdotally, giving examples of the friends of my children and the children of my friends, I can literally name for you young people who have gone to China and learned Chinese, who have worked on water projects in Vietnam and learned Vietnamese, who've taught English in Japan and learned Japanese, who've worked on development projects in Central America and learned Spanish, and expatriate musicians who are living in Berlin and have learned German. They all learned the other official language first.
Learning French is not a barrier for anglophones. Learning English for francophones is not a barrier to the rest of the world. It is a bridge to the rest of the world. There is one amazing thing I've learned from all those young people I have met over the years who have, in many cases, gone through immersion, or in the case of francophone Quebeckers have learned English often outside the classroom. It's that learning a second language at a young age demystifies language learning. It becomes, for a young person, fairly natural that if you find yourself in an environment where people are speaking another language, you set to work to learn how to communicate with the people around you. In terms of multinational corporations that have jobs and offices around the world, I have read that one of the values that Canadians bring to those positions is often language skill, and with that, a greater cultural sensitivity than is often true for the unilingual person.