I will start with my opinion over potential candidates:
Sweden
Spain
Italy
Each of these countries is threatened by:
Sweden: Illegal immigration that very quickly destroyes its social structure and system
Spain: Illegal immigration and the prospect of direct threat from arabic countries that consider it as their lost kingdom
Italy: Luck of governance and great social instability after years of democratic ruling and national suppression.
In the countries could be Greece, if and only if could provide the national momentum that is needed to create a revolution. However it is unlikely that to happen since the Greeks are divided by forces beyond their control.
Potential candidate I see Sweden since its social structure it will be the first to collapse under the pressure of immigration and asylum seekers. They also have the potential of feeling in the future as the
protector nation of Europe due to their protectivity to what Europe stands.