I don't think there will be a great hemorrage from FD to EK. As EK lets even 777 qualified pilots do a almost full course (because evidently only they know how to correctly operate), it does not save any cost, compared to a DEC. And the FD transition guy would need to be replaced, costing another course.
I believe that guys joining the lowfat-EK will be stuck there, as has been seen in other parts of the world with the junior/regional partners, much to the displeasure of their pilots.
For FOs within EK it is unfortunately some kind of gamble. If the business picks up in the not too distant future, it might be that the upgrade dawns at around 5 years. If however the upswing takes a little longer, it will be another story. Many cadets will by then have the hours, inclusive the new joiners, because emiratisation will not stop. These guys will be given a upgrade irrespective of hours, experience and operational success.Their departure will also need replacement on the FO side, and this can be achieved by leaving the expat FOs right where they are. For a eventual small time lag DECs will be cheap and available .....
Let's just hope EK does not defer the intake of heavy metal too much ....