1. Mainstream parties and politicians on both the right and left will adopt Le Pen's immigration platform, and ride it to success
2. Men such as Le Pen will achieve success.
3. France will become an Islamic state.
I do not particularly care for Le Pen's distaste for democracy or his authoritarian tendencies, and would prefer scenario 1 to scenario 2. But I would infinitely prefer scenario 2 to scenario 3, and this goes for all Western nations, not just France.