And what will China and Europe do with that money? Invest it in the U.S. of A. Further, a lot of European companies are American companies, also. Buy from Dalmier, help Chrysler. Buy Opal, help Ford.
Money is like water. It finds its own level. All the Saudis will do if they ditch their American assets (note, they threatened to remove their "Western assets," which includes Europe), is pay higher prices for goods, receive lower interest for cash, with the balance being retained by middlemen dealing with the U.S.