Both China and the Arab oil countries are already working to become independent of the Dollar switching to the Euro to do their business.
This is true, but I think those gulf countries realize that a (gosh, I can't think of the word, so I'll just use "united") currency will not work, just as many economists believe the Euro will be failing soon. I can't remember the reasons, so please forgive me, but the Euro just isn't as robust as the dollar is. Granted, the Euro and other currencies are still worth more (if I remember correctly), but the dollar is supposedly more stable in the long term. Last I read, China is still looking to be independent, but those Arab states, I think, realize that a regional currency would not work for them. For one, there's not a single Arab gulf state that really gets along with another. The Saudis look down on the Bahrainis, UAE is a tourist center that relies on Europe, Asia, and the States for its income. There are even arguments among the states if you expand the geopolitical boundaries, such as with Syria and Lebanon, Iraq and Kuwait, etc. So I don't think it would work, or work to their benefit, if they rely on their own currency.
Also, keep in mind, it's wise for other countries to not rely on the dollar, so it's not necessarily a bad thing that they're trying to become more economically independent.
I can't think of a single Arab country that would even want and could afford the U.S. debt except for maybe Saudi Arabia, and if that were the case that would actually work in both states' favor.