You are leaving out a whole lot of stuff that can seriously alter the landscape.
Companies buy from China because of a game of relativity with other Asian countries as well as the US. Within the current framework China is cheaper. Emphasis on the 'within the current framework'.
What if the current framework changes?
1. The Chinese currency is seriously undervalued. What happens if the price gets corrected, even 5 years later? The price of goods (to the US importer) jumps about 40%+
2. What happens if we sign free trade deals with all of the Asian competition, such as Korea, Singapore, Taiwan, etc?
As it stands, trade is taxed by the exporting country, then you have all kinds of other things to spend money on ie govt related obstacles, then you have shipping, and import tax, and all other kinds of tax on the US company.
If Congress passed one law giving tax benefits to country X, Y, or Z, China would lose out.
In short though, between 30% and 75% of the wholesale cost of a product is in the form of govt regulation, taxation etc. And that is not all the US govt. In other words, a $10,000 product would actually cost $17,500 to purchase and import.
With a FTA, such as the one we are going to sign with Singapore next week, most of those barriers go away.
If the competition has an FTA with the market, but China doesn't who wins? Given the right conditions, not China.
Just those two things alone, 1. the currency pressure to revaluate, and 2. shifts in the global system can throw a real wrinkle into China's plan. Just with those two things though, China has serious upward pressure on them, and the other Asian countries have serious opportunity for downward pressure. Labor costs are a very small part of the system. In this scenario the competitive advantages might be too much for corporate America to pass up.
Just figure this: what is the difference between a 40% increase in the prices of Chinese goods (to US importers) and a (lets just estimate) 25% decrease in the prices of products from elsewhere in Asia?
So, in other words, I would venture to say, that Wal Mart, and most likely quite a few others will start to shy away from China over the next few (5) years.