Either candidate must work with one of the mainstream parties in France. I suspect Le Pen will find it harder. Whomever wins will have a steeper learning curve than an establishment candidate. Remember that although Jimmy Carter was a Democrat, he was an outsider, and it showed.
The international fascism of Le Pen, Bannon and Trump is the salvation of militarism as it becomes obvious that terrorism is a law enforcement problem rather than a military one (I suspect the Republican Guard that made ISIL so fierce has already been killed off). It is time for the left to take a stand, not with the neo-liberals for ordered globalization but with the inclusion of Francis. There may even be room for a new socialism, which is already standing up to Trump.