It is interesting to note that the French language in Canada has remained vibrant and strong for the last near 400 years.  This would bring into question the not as of yet verifiable proof the last 40 years the French language laws have been in place has saved the language.  I would say the previous 110 years to the laws, and the 97 years prior to becoming a country had a significant and verifiable impact.  What has been demonstrated over the last 40 years is that English Canadian culture in Quebec has been negatively impacted, resulting from the application of these laws.  This is a land of extinct cultures, and cultures under threat are treated with concern, with the exception of Canadian English in Quebec.