Honestly, the title of this news article is a bit misleading and a lot of French consider that this move is in the wrong direction. Policemen are going to have the right to call who's prosecuted and who's fined.
Like many friends and french fellows, I've been smoking for 10 years and buying on a weekly basis but I never had any issue with the police. I don't think a single one of all the dealers I've known has ever been arrested but I may be wrong. Streets smokers are often the ones who get caught with tiny amount and that new law won't help them.
I think we'll likely need another 10 years before anything moves, but I may be wrong!