<<You have this backwards, or Congress does , they are pushing China with every lever that they have to make the Dollar cheaper against the Yaun.>>
China's a special case. They claim they want China to revalue renminbi to make it harder for Americans to purchase Chinese goods and easier for Chinese to buy American. Allegedly, Western Europeans want the same revaluation. Probably this is just empty posturing by the U.S. government to please its manufacturing and exporting base, as it has had virtually no effect on the Chinese government other than a very minor upwards adjustment some months ago, nowhere near what the U.S. government claimed it was seeking. It makes very little sense to me that China would play with its own currency simply to please the U.S. - - would the U.S. play with ITS currency simply to please the Chinese? I think you are placing way too much reliance in your argument on the US "wanting" China to revalue.
Furthermore, I'm not an economist, but it seems to me that even if China DID revalue, this would affect the dollar marginally, whereas a slackening in worldwide demand for the dollar caused by re-pricing many if not all mid-east oil contracts in non-dollar currency would have a much more dramatic effect on the dollar. I'd obviously be in a better position to argue this point if I knew the total amount of US-China trade, and the total value of all mid-East oil purchases over a single, recent common period of time.
Your long-term predictions about China's, India's and America's long-term prospects in the import and export trade are way beyond what I would be able to predict, and they don't alter in any way my explanations for the invasion and occupation of Iraq (and possibly Iran) as generated by a fear of future insufficiency of oil supplies.
Whether or not the US increases its exports over time, it is still gonna need oil desperately and so will other big countries developing much faster than could have been anticipated fifty years ago. If there isn't enough oil for everyone, (and that's a big IF,) the US would then be in a much stronger and better position if it occupies the oil fields and decides who gets what and for what price. That is basically deciding who doesn't get any, and that is an incredible amount of power. The U.S. would have to be crazy to let that power fall into anyone else's hands.