FOs will only have an MPL for 2-3 years. When they get to 1500 hours, they will get an ATPL. Since an airline will have pre-selected them and given them a job and bonded them for 3-5 years, the only ones who will need to worry about employability for their second job are those made redundant before they get 1500 hours. These will have a type rating and they will be able to do 3-6 months of modular training to earn a single pilot ME/CPL/IR. I wouldn't write them off as dead in the water. An FO with an fATPL who is made redundant is little better off, though he has a shot in to DEP schemes if he got past 500 on type.