Deficits in the U.S. have become staggeringly large, and if this country doesn't correctly deal with them then the dollar will itself suffer. China, for example, might be prompted to give up on the dollar as a reserve currency, turning to gold instead. Greece's current problems are a dress rehearsal for what could happen to the U.S. down the road.
The U.S. economy and currency are not automatically doomed, however. But the only way it will survive its debt mess will be through economic growth. This is possible, especially if the U.S. figures out how to exploit the major opportunity that exists to participate in the economic growth of emerging markets around the world.
So, he still has hopes but he also sees weak points that greenback skeptics know well.