Actually the J-20s would be vital maintaining air superiority over Taiwan. J-20s would be responsible for shooting ROCAF aircrafts already in the air (clearing the sky). Once the majority of Taiwan's F-16s were to be shot down, the J-16s and J-10s could then move in to conduct SEAD operations (using mostly YJ-91s). Amid SEAD, the J-16Ds would try to blind Taiwanese radars before other aircrafts blow them up. The PLARF would simultaneous destroy key immobile infrastructures like non-nuclear power plants, bridges, railways, highways, airports, etc. Following SEAD, the J-16s and J-10s would should theoretically being able to track down every army formation and obliterate them with cluster or laser-guided munitions. If things go according to plan, the PLA joint forces should be able to cripple Taiwan's air, naval, missile, and air defense forces before US and Japanese reinforcements arrive. However, lots of could still go wrong in the process, say Taiwanese HF-2E and YunFeng missiles successfully cripple a number of key PLAAF airfields, or say Taipei decides to carry out the nuclear options by targeting nuclear power plants in Fujian. Ultimately, your enemy gets a vote, too. Also, Taiwan could simply hide its mobile anti-ship units in caves and wait until the PLAN begins amphibious operations. Under these circumstances, you will need J-20s and J-16s be in a constant look out for mobile launchers. However, as US invasion of Iraq has shown, it is usually extremely difficult to track down mobiles missile launchers.
