How? They either fire on them and down the plane or the pilot makes a break for Japan, S Korea, or at worst the Philippines. Either way jets will scramble from Japan and S Korea. We have leverage here if China doesn't want to start WWIII. If they do anything to harm our plane there will be spiraling retaliation.

Now I guess they could pull a mid-air hijacking or have a sleeper onboard, but my money is on her landing without incident in Taiwan.

More likely is an assassination Russian-style with poison or radiation, that is timed to take effect when she is back in the states.