The French language was never in danger in Quebec, statistically speaking. The French speaking population of the province has always hovered around 80-81% throughout its over 200 year history.
French mother tongue in 1901: 80%
French mother tongue 2006: 80.1%
Source: Canadian Democracy, Stephen Brooks, p.383
"A 1970 survey by Guy Labelle estimated that 35% of the commercial signs in metropolitan Montreal were in French only and 11.8% in English only'-Marc Levine, "The Reconquest of Montreal: Language Policy and Social Change in a Bilingual City", p. 200
Professor Emeritus and expert demographer Jacques Henripin predicted in the 1970s that without language legislation, the French speaking population would still at roughly 77% by 2001.