FullyFullyReady is correct, post final line check derestricting the MPL licence from the partner airline is a paperwork exercise. The MPL holder is free to go elsewhere.
And they have:
http://www.pprune.org/terms-endearme...ml#post8714331
MPL students bust transfer myth - 10/22/2014 - Flight Global
Prospects seem pretty good, relative to the small number of MPL holders and the short amount of time they actually hold that licence.