Actually, while you are correct, manufacturing is starting to become quite expensive in China as labor costs have been skyrocketing. Perhaps the struggling Chinese economy might buy manufacturers some time, but they know that diversifying away from China is a must. Vietnam, India, Brazil (lesser extent), Indonesia, etc. will benefit from that. Hell, even Turkey will get a piece.
I think Chinese government knows and they are preparing for it. China is also going for high-end, high value added products and is pushing hard for servicing industry.
The point is that a country will go through high growth, low end manufacturing to jump start its economy, eventually it will go for high-end, high value added products. Currently, there are only two countries that able to do this, United States and China.
The advantage for China is that China has 1.4B people to consume, the market is big enough to allow full supply chain to grow. Chinese companies is able to access such large market, which allows them to invest and grow. Something can't be said to Vietnam, Indonesia.
The problem of India, it is they are very inefficient and their basic infrastructures are very poor. They have large amount of people uneducated and their electricity grid is very weak.