Front National congratulated, Geert Wilders (PVV, Netherlands) thinks the Netherlands should have such a referendum too, and the PVV was elected 3rd strongest party in the elections 2012 and is currently ahead in many polls (next election before April 2017).
Just a thought: ISIS is not stupid, if they are able to strategically make another terrorist attack months ahead of the French elections, what party will that help? The Front National does have a chance of winning, even if for now it seems unlikely, but hey, who would have thought Trump could win the the Republican nomination half a year ago?!
Anti-Islam sentiment will result in more people fighting for ISIS, re-nationalisation will make the War on Terror less organized, focus will shift from fighting smart and doing so heads on to isolation and protectionism.
Alternative für Deutschland (AFD) in Germany, anti-EU sentiment from the CSU (sister party of the CDU (Merkel's party) in Bavaria), Austria came close to electing an anti-European right-wing president... The PVV (Partij voor de Vrijheid - Party for Freedom) in the Netherlands, and in countries where the EU-hate is not coming from the right side, it often comes from the left.
The sentiment for Re-nationalisation is a widespread phenomenon.
We can discuss all we want about how the EU failed, but to say Britain in this case is not an important example of what can happen in other European countries is naive... I don't want to paint the devil onto the wall, but look in history how often times "we stumbled into war"[1] - I don't think we are there yet, just to make my point - never underestimate what can happen and looking at all the facts, we have all the reasons in the world to (at the very least) worry.
[1] To stay in Europe: Also consider the Nato/Europe-Russia conflict, East Ukraine...