That question is very relevant for a demographer, and I thank you for it.
I have already emphasized under–fertility, but I don't see how we could impact that factor. A decision won't be made tomorrow that, from now on, only francophone mothers will be entitled to family allowances. Pro-birth policy cannot be applied to a single language group. It would not make sense. So we can't work on the fertility aspect. The only two aspects we can work on are immigration and francization of immigrants.
A study Statistics Canada published a year ago slipped completely under the radar. People usually don't like bad news. That study shows that you may well increase the number of francophone immigrants, play around with the numbers and linguistic composition of immigration, but that has practically no impact. Researchers have formulated hypotheses to determine to what extent the decline would slow down if immigrants were francisized more, and they found that this only slightly slows down the decline, but that is all.
As a demographer, I must tell you that, unfortunately, all the hypotheses formulated over the past 40 years have had the same result. We are not pessimistic because we want to have pessimistic outcomes. We formulate hypotheses on fertility, mortality, immigration and linguistic behaviour. We use those hypotheses to create scenarios. No one has ever questioned those scenarios because they have all turned out to be more or less correct. We press a button, and we get an outcome that is not very pleasant. That is all.