Yes things can (and hopefully will) change in 5 years, but the phenomenon is still worrying. In a way it's a good thing that Brexit happens and I almost wish for it to go terribly for the UK so that it can help weaken their anti-european stance (sorry Brits).
The popularity among the young population shows how clever the FN strategy has been for the last decade. Older people do remember the roots of the party and aren't really fooled by the new coat of paint. But for the younger ones, the FN is just another political party.
Also it's one they can use for contestation, and with the almost complete disappearance of the far left (at least PC, FO etc), the FN is the obvious "anti-system" vote.
It's that despicable habit that voters have of using elections as a tool for expressing discontent rather than a democratic vote. I was discussing with a member of my family who disliked all candidates, and despite not supporting the FN he wanted MLP to lose "with the smallest margin, to send a message to the future president". Yeah, like that's not dangerous at all. And his wife said "even if she wins, it's not the end of the world". Well maybe not the end of the world, but most probably the end of EU.