Grantley, the dollar would have to fall along way to make a dent and a difference in the $10 trillion (as of 2006) debt the US presently has.
There are at present many deals within the world enconomy that are no longer done in dollars, especially in the private sector. As for the price of oil, well its posted in Dollars but that doesnt mean its a real dollar. The changes in the dollar against major world currencies is main push behind oil prices, you look around to see how the dollars doing and change your price accordingly. At the present time the oil price is related to the EURO and its strength against the dollar.
Everybody in the finance & Oil business knows, Dollar down = barrell price up, its always been that way.
And lastly there are other reasons other than purely financial ones that will affect the Dollar Peg, there are alot of countries out there that would prefer not to have there currency linked to the dollar for political reasons. As long as the dollar is strong, the political arguement doesnt come into play but a weak dollar for a long period of time will make the political card stronger.
It going to take only one big player to want to get rid of the dollar peg, and beleive me the others will agree.