Between Strasbourg & the northern frontier with Germany it still persists, getting stronger as you move north. South of Strasbourg it pretty well fades out. The kids up here speak it less and less, too.
Latest Maigret gem is fil-en-six: Before WW2 the strength of spirits used to be indicated by loops of string knotted round the neck of the bottle, presumably for people who couldn't read the labels. The more loops, the stronger the drink. Fil-en-six was eau-de-vie, around 40% alcohol.