Since Taiwan is not adjacent to Mainland China, portion of air transportation must be larger than that between Hong Kong and China.
On the other hand, Hong Kong has East Rail Line, which is connected to Mainland China ,and High Speed Rail called Guangzhou-Shenzhen-Hong Kong High Speed Rail is under construction. So, portion of rail transportation is expected to increase.
By the way, there is a plan to construct an undersea tunnel between Fujian(China) and Taiwan. Though I don't know whether or not it is feasible, airlift portion between China and Taiwan will decrease after completion of the tunnel.
