The real danger isn't a coup, but a subtle pronunciamiento, the distinuguishing characteristic between the two being that the coup seeks to change the regime, while the pronunciamiento seeks to change the regime's agenda.
Europe's tolerance towards of the "democracy bending" behaviour of Silvio Berlusconi is a cautionary tail. Money is a sign of Poverty - Culture Saying
As Migeru has pointed out the possiblity of actual military action is almost nonexistent, but I wouldn't dismiss the possilbity of things spinning out of control. This last spring a poll found that 54% of Spanish favored the military occupation of the Basque country if there was an autonomy referendum a la Ibbaratxe Proposal. As well you now have an increasing military role in keeping Ceuta and Melilla secure.
There's an old saying, "Why buy the cow when you can get the milk for free?". Because the Spanish are incredibly sensistive about the idea that there remains any lingering reamainder of the fascist past, I suspect that before there was military action, public opinon would cave to restore peace. And the situation in Catalunya woul become more and more like the situation in the Basque country.
It's not cowardice, it's a deeply understandable aversion to conflict. And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg
