A note to our readers: this is /r/AskHistorians, and we're here to talk about history, not current events. If you want to make a post about the current economic and political structure of Spain, please reconsider.

The fear of bloodshed and the realisation that the Spanish regions are very interdependent keeps them from Balkanising. Even during their "Balkanised" period, the Civil War, regions like Catalonia and the Basque country were not clearly in favour of independence. They were divided and several other factions in the republican camp were also not in favour of their independence.

During his dictatorship Franco suppressed these independence movements as they were part of the democratic republican opponents during the civil war. After Franco died, the regions in Spain gained the right to educate in their own language and live according to their own customs. That created a national consciousness for the regions that was maybe even stronger than it was before Franco.

The independence movements that didn't use violence were legalized and made their case in the democratic arena. Over time the central government in Madrid lost most internal powers to the regional parliaments and governments. Catalonia and the Basque Country have become autonomous regions and only have no powers over defence and foreign policy. They already are virtually independent.

A question on independence can't be sanctioned by the regional parliaments alone, but needs to be supported by the national parliament. Large parts of Catalan and Basque society do not want to gain independence, so getting a majority for their case in the national parliament is very difficult, maybe impossible.

One of the regional complaints is that they pay a lot of money to support the poorer Spanish regions. That might be the case but Spain receives a lot of EU support, long before the financial crisis triggered another financial stream. The richer northern regions are going to loose all that financial support and probably would become a payer instead of a receiver of EU money. They simply do not realise that they are now at the receiving end of the European 'Robin Hood' mechanism.

NATO and EU warned Catalonia and the Basque Country that, if they unilaterally declared independence they needed to apply for membership as new countries. Since Spain is an important member of both organizations, they can obstruct membership. That would bloc two vital areas where the regions have no independent powers: foreign policy and defence.

It is highly questionable what the real gains are for Basque and Catalan independence. They are already almost independent. If they do not have to answer to Madrid, they have to answer to Brussels or Washington. It also could trigger a wave of irredentist movements in Europe that would make Europe even harder to govern than it already is. They do not all of a sudden become rich and happy because of independence, they just have to answer to new masters. So there is limited national support, a bit more regional support and little European support for this project.