I think that Germany, if attacked by al-Qaeda, would follow the "Madrid model" and blame the US for making the world a more dangerous place. Remember, they have troops supporting our efforts in Afghanistan and they could publically pull those out in an similar act of cowardice and short-sightedness.
Then let's hope it happens after Schroeder and the SPD/Green coalition is kicked out at the next elections and a more sane CDU or CDU/FDP coalition is in charge.