CX F inventory has decreased dramatically over the past year on basically all routes - the reason being that they have decreased the amount of F seats in the network. 744s with 9F were replaced with 77G with 0F.
SFO went from 15F across 2 flights to 6F across 2.5 flights.
LAX stayed at 18F across 3 flights to 18F across 4 flights.
ORD went from ~9F across 1.5 flights to 6F across 1 flight (averaged).
NYC went from 24F across 4 flights to ~21F across 5 flights (averaged).
Not hard to see why availability has decreased.
Obviously the somewhat bright spot here is that BOS is launching with a 4 class cabin which should mitigate some of the damage, but it's still a decrease of 9 F seats per day from the US to HK, which is a LOT when there are only 51 now.