Actually, the Chinese are already in Afghanistan. The Chinese won a bid for a copper mine in Logar province, but according to a recent U.S. survey, there are over a trillion dollars worth of metals and minerals in Afganistan, "U.S. Identifies Vast Riches of Minerals in Afghanistan", James Riesen, New York Times, 2010-06-13.
What if the U.S. gets China more involved in extracting resources from Afghanistan? Would the Chinese have to bring in their own military to protect their interests? As the Chinese got more and more involved in mining, would they have to bring in more troops? They've managed to take over Tibet; would they be able to take over Afghanistan? Then the Taliban would be direct their ire against these new invaders and the U.S. could slip out.
There are a couple of caveats about this.
First, Logar was the province where several Afghani groups destroyed a 350-vehicle convoy, including tanks? Would the Chinese fare any better? Would they want to take on that kind of risk?
Second, if China takes over Afghanistan, they might lock out others from access to the mineral riches of Afghanistan. This could put U.S. companies at a big disadvantage.
A better way would be to promote the mineral wealth as a means for co-operation among all interested parties: large companies that want access, Afghanis that want jobs, Afghanis that want peace, and Afghanis that want political power. It really comes down to would you rather fight and keep Afghanis poor or would you rather find out ways to benefit all interested parties.