“If there is a slowdown in flying”
Unlikely if you are on COS 18. You will be cheaper to employ than any other pilot in the company. Therefore those in the future employed on COS18 contracts will be guaranteed high hours as they are such a big saving over Standard Contract and B scale FO’s.
I don't see it happening like that. COS18 pilots will only get hours above the threshold once all the other pilots have been rostered up to their overtime threshold. They will get less pay than advertised.