no one is waiting for a retention bonus. if you are at envoy as an f/o and approaching three years seniority and live around NYC and dont want to commute to ORD or DFW then Endeavor is a option, by 2018 if you get hired today, you will be 40 thousand dollars ahead than you would be at eagle and off reserve faster also.
those flowing in the next three years, short of all hiring stopping at aa, they are not leaving. they will wait for the flow.
in between these two groups is anyones guess.