well, I disagree but I am not a French expert as I have stated and I believe at least to some extent that your views are somewhat influenced by a desire for a uniform France, no offense intended.
the one place where you, as a rule, do not learn non-standard varieties or dialects is at school. if you were to say university as part of a (voluntary at that) retro movement I would agree but school is really the one point where either the local variety/dialect takes over or the standard variety is imposed. the term 'mother-tongue' is actually quite acurate. children (up until a certain age) have an innate desire to sound like their mother (oddly enough even if the dad is around just as much, as I have noticed) or like other kids. last thing on their mind? reviving odd and old varieties and dialects.
as far as Latin goes: it has been spoken continously since before it had been fixated into Classical Latin (as written (!) by Caesar and Cato and the other fellas). it has merely evolved into the Romance Languages as we know them today. as far as linguistic continuity is concerned the Romance languages are a form of Latin. 'Classic' Latin, like the Latin you might know from school, has (some say) never beeen spoken. Vulgar Latin (as the Romance Linguists understand the term, this is not to be confused with "Latin Roman soldiers spoke around 100 AD", "Latin used by Merchants in Castrorum Regensum in 499 AD" or sermone vulgaris) is the root of the modern Romance Languages.
this (linguistic) term has a lot of problems. it has to encompass all of the dialectical features throughout the Roman reign (some odd hundreds of years) as well as the aftermath of it. Latin (Vulgar Latin) looked at this way has actually never been spoken by anyone, anywhere at any time. it is a construct.
it holds true, however, that France, Portuguese, Spanish, Italian, Romanic, etc are versions of Latin and that Latin has, indeed, survived until today.