How is the PE inventory? Is it getting full on most flights?

The reason i ask is since CX is expanding PE to most long hauls, doesn't it make the chance of upgrading to J (from PE of course) now almost impossible?

My reasoning is this:

(1) Economy sale would now be limited. For example, a family of four picks a December 22nd flight, which appears almost full on Y causing price to be just a few hundred dollars cheaper than PE. The family would either bite the bullet and get PE or choose another date.

(2) Assuming Y is overbooked, people would move to PE. But that's based on Y inventory.

(3) Here's my assumption - PE would not be be overbooked (in my example for number 1, i'm thinking the family of four would choose another day but with Y class that has a lower price/bargain, not just a few hundred difference with PE). With that it appears the chance of the paid PE now have a slim chance of upgrade to J. Not unless, Y is overbooked 200%, causing PE to be overbooked as well.

Basically, one other way of figuring is out, is that has there been a lot of operational upgrade from PE to J?

Thoughts?