A decision by a regional court in Spain, although an important step will be unlikely to influence the remainder of the country. The bank is also going to appeal and it could be overturned. These autonomous regions tend to be a law unto themselves. Witness the Valencia land grab issue.
In any case I have not heard of to many banks pursuing negative equity on a large scale yet. However that might change as they are forced to sell off repo. stock substantially below the guaranteed amount.