The FN was created in 1972. until 2008 it was run by Jean Marie Le Pen, a man that make Donald J. Trump look mentally sane. there is no way JMLP become president: and yes, April 21, 2002 was an accident. Le Pen himself later declared he had been taken by surprise and that him and the FN were absolutely not ready to govern France.
That make 2016 the FN best chance. Down in the French politics thread (in chat) we examined such scenarios. Let's say Macron is never born in 1977 and then France history proceeds as per OTL until 2015 or so. Hollande's PS is dead and buried, since hollande presidency was an utter disaster. Let's say the PS candidate is either Manuel Valls or Benoit Hamon. It doesn't matter, because they hate each other, plus Hollande. And Melenchon. this makes the left entirely fractioned.
So just like in 2002, it is the French right versus the Front National. Then Fillon scandals happens in February (as per OTL), just in time to ruin his candidacy but too late for the French right to pick Juppé or somebody else. With the left dead and Melenchon too much of a loudmouth scarecrow to picks enough vote, Fillon versus Marine Le Pen for round two.
Then with a little help from the Murphy law (if everything can go wrong, it does) Marine Le Pen hammers Fillon with its scandals during the debate. Add a small scale terrorist attack at the wrong time and voilà, freakkin' Marine Le Pen is president, and France is screwed as much as the United States.
Major shitstorm follows.
As for me, I picks my wife, my kid and my elder sister and get away from France. Either I settle in Barcelona, Spain; or at La Réunion island 5000 miles away. But metropolitan France is dead to me.