Incorrect. If PLA's air dominance enables it to land on Taiwan's beaches, then it can defeat ROC counterattacks from the air.
Assuming the US does not intervene, PLA will dominate air space over Taiwan, any attempt at counterattacking occupied beach head will be destroyed by airpower. The only way to survive would be to hide under ground or in urban areas. measures as you suggested, such as artillery and drones, are a non-issue because without air cover, they would not even know where to fire or how to coordinate their fire.
Assuming the US does intervene after PLA landing, then the nature of the conflict will change and PLA will likely just give up trying to protect their beach head and focus on defeating the US. If the PLA can win that battle, then no further action would even be required against Taiwan, the latter will simply surrender. The loss of landed troops is an acceptable price for defeating the US on the pacific. If the PLA cannot defeat the US, then no amount of landed troops will change the outcome of complete defeat. I have alluded to this possibility in my earlier posts, where the PLA could conduct a landing operation early to force the US to choose between prematurely engaging the PLA and to avoid getting involved, which would precipitate a collapse of ROC defence.
