If catalonia will split with spain. Will they stay in european union and in euro zone? Or they will become completely independent? Separatist war in western europe would be a disaster.
If the Catalans actually manage to gain independence, they will be a part of the European Union, Schengen Zone and the Eurozone (just like the case if Scotland becomes independent). Also, Catalonia is situated in the Western part of Europe, and not in the East. Anyway, the chances of a separatist war are next to none. Both the sides have no interest in waging a war.