Motive and outcome:
Who and why would they burn down Notre-Dame?
Islamic groups burn it down as a show of disdain and hate for Christians. This in turn will start a race war in France. There are roughly 3.5 million muslims in France. This will force the French government to act to control both sides. No more protests, more of a police state, and harsher penalties for hate speech and thought. This is NZ all over again.
What's' next?