It's a good question, explored today by FP's Andrew Small. According to Small, China has it's eye on setting up shop in post-Karzai Kabul:
Hamid Karzai's derailment of this week's planned U.S. peace talks with the Taliban may have been a disappointment to Washington's hopes of ending its longest war -- but it disappointed Beijing, too. China welcomed the breakthrough in the Qatar process, and sees a political settlement in Afghanistan as increasingly important for its economic and security interests in the region. As a result, China's support for reconciliation between Kabul and the Taliban has become a fixture of its burgeoning diplomatic activity on Afghanistan's post-2014 future.
Over the last year, China has been expanding its direct contacts with the Taliban and sounding them out on security issues that range from separatist groups in the Chinese region of Xinjiang to the protection of Chinese resource investments, according to interviews with officials and experts in Beijing, Washington, Kabul, Islamabad, and Peshawar. While Beijing would like to see the reconciliation talks succeed in preventing Afghanistan from falling back into civil war, it is not counting on their success, and thus is preparing to deal with whatever constellation of political forces emerges in Afghanistan after the United States withdraws.