If GBA are going to be paying the UO COS21 then good luck to them. Won't find any suitable drivers for that kind of money, everyone would be better in their own countries or Middle East. That will have to start looking elsewhere for the leftovers. It won't be great for business.
Any left over 73 captains will just go to China once the pandemic ends. Even their new COS is better than COS21. FO wise they should have a few leftover/angry at COS18 local candidates but the big thing will be any form of decent experience on type.
In the end a bus is more suited to a cadet/low experienced pilot than a 73.