I think the dollar is being driven down intentionally to cause fear. Now we hear subtle calls for getting rid of the dollar. To establish a global currency when things are going well cannot be done. But if things are miserable, people are afraid and scratching for food then introducing a new currency should be easy as people will see it as a relief rather an infringement on the their liberties and national pride.
On the other hand I know too the U.S. has a military no other army in the world can match or defeat. But there is a way to bring this country and Europe to it's knees and thats by hitting the economy. Just like they tried in 9/11.
Just my 0.2 cents worth of conspiracy theories