The idea I was trying to relate would imply that after X time, staying in their realms wouldn't give them anything, but they'd still have their units, Y (much longer) time to go about and use these units in a military manner (should they chose), effectively granting a total of X+Y time. This Y time is a buffer zone where it is painfully clear that there is nothing left for them to stay for, and as such they can accept that fact and then move on to do something about their fates.
