Under current standards, an elite job is a job for life. The new business model is becoming schedule 10 NC cookies, win 4 conference games and get your NT spot. In the ACC, you can't avoid making the PI. We have 10-17 elites getting to the PI.
Your A+ should be reduced if you have ONE losing season, miss the NT twice in 4 seasons, don't make an Elite 8 in 5 seasons. PI should mean nothing in the firing process at any A-, A or A+ level. For A- and A, it would be a matter of how generous you want it to be along the same structure. And if you win less than 16 games for 3 straight years, that could also fit into the equation.
The firing threshold could be tied to prestige decline if a structure is in place. For the elite, if you decline from A+ to A, you're fired if you don't regain your A+ in, say, 4 seasons or, if you decline further. A scale could be developed for every grade level. Shoot, D's shouldn't be fired unless they have 6-8 losing seasons in a row.
Am I off base here? Throw some suggestions on top of this. And if it sucks, say so.