i agree, they wont station everything in Asia and i surely agree PLA does not need same amount of J20 as F35.
But you mindset is still positioning 5gen as day-1 weapon. This mindset makes some sense when PLA is up against some mid level power such as India or Japan, however in high end conflict you cannot expect to crush the enemy air power in a short period of time, then move on to use non-stealth a/c to carry out strike missions. It will always be a highly contested space filled with 5th gen, where 4th gen a/c simply does not have much survivability.
Some time ago i ran some simulation with CMO - not the most authoritative war game simulator i admit.
First if you run 24*J20 against 24*F22/F35, you more or less get a 1:1 result.
Then you throw in 24*J16 on the PLA side, guess what happened? nothing. Basically those J16 are just collaterals damages. With all J16 shot down in the process, not much impact at all to the exchange rate of J20 vs F22/F35, and if you add F15 to the US side, same thing.