The Spanish Govt announced last week they they are going on an austerity drive - see
BBC News - Spain budget: Cuts to total 27bn euros this year
Spain doesn't seem to have any obvious military threats against it that would involve the use of air power and I don't see Spain engaging in any significant new overseas adventures for the time being.
I know the Spanish Air Force want MJV for pretty much their sole use, but is delaying the opening of Corvera until the economy improves and just sticking with San Javier an option ?