A LIFO plus option is most definitely viable. Some sickness adjustment to get rid of "targets". Proportional adjustment to eliminate disproportionate reduction of female pilots. Using sickness etc as a sole method of CR will not happen....it has far too many loopholes and will potentially tie up the airline in litigation for years.
The number will come down as well. 727 is worst case. TUI, Ryan and BA have ended up with far more realistic figures. TUI is zero. There is huge pressure being put on Johnson to end "fire and rehire" which is morally repugnant. This has some mileage yet before we see a final proposition.