The decline from the 60's to the 90's is very analogous to Detroit. The difference is that Quebec is allowed to give extra visas to attract about 45,000 immigrants per year to Quebec, mainly from the Francophone world, through special immigration quotas given to Quebec. About 3/4 of these immigrants settle in Montreal.
http://www.micc.gouv.qc.ca/publicati...syn_an2010.pdf
This program is not ideal [[many immigrants are from tertiary areas of francophony and about 20% leave for other parts of Canada as soon as they can), but it has helped stanch the deep population drop of Detroit and the stagnation of Metro Detroit as a whole.