Being married to the head of a rather significant entity here in the U.K., and owning my own business in the U.S., I can assure you that simply because you have managed to maintain pulmonary functioning in your position for a time certain is NOT going to bring you promotion in my world.
In my world, I absolutely agree with you, Diplome, it's a meritocracy combined with a slippery pole - one wrong move and you can slide down a long way.
However, the concept of seniority is the curse of the airlines
If mixed fleet will offer promotion based on merit, then that is a good thing.
But we will see.