Yes, if Spain pussyfoot around and start without a striker again, France can make them pay.
For one, they won't have as much possession as they enjoyed in the group games with this bizarre tactic as France know how to keep ball too, and secondly France are also a much better counter attacking team than any opponent Spain has faced so far.
IMHO they lost to Zidane, not so much to France at the WC 2006. After Zidane retired that French NT went crap. But this new squad is still much better than the 2010 WC French team and Spain will have to earn their goals the tough way. I'm thinking a 2-1 for Spain but an upset would definitely not be surprising since France is an offensive-minded team.