The European debt crisis in a picture

From the New York Times (by way of Simon Johnson), a beautiful (and scary) picture of the various debt connections among European nations. (Best to right click and download and then open so you can easily zoom in and out as the picture is mighty big.)

My question is - what happens if the Euro does collapse? Do European nations have well-planned emergency measures to restore the Franc, Deutchmark, Lira and other European currencies quickly? Somehow I'm not feeling reassured.