THE HAGUE—If the European dream is to die, it may be the Netherlands that delivers the fatal blow. The Dutch general election in March is shaping up to be a defining moment for the European project.

The risk to the European Union doesn’t come from Geert Wilders, the leader of anti-EU, anti-immigration Party for Freedom. He is well ahead in the polls and looks destined to benefit from many of the social and economic factors that paved the way for the Brexit and Trump revolts.

But...