The forsaken established their kingdom through guerillia warfare and will most likely kill most of the new settlers through ambushes.
Orcs will have to be watched the most, since they are the most bloodthirsty
The Tauren might tolerate an occupation for a time, but certainly not for long
The Darkspear will wait and strike when the time is right to reclaim their land.
Neither side has hopes of ever achieving total victory unless they wipe their opponent out entirely, and even that is almost impossible in that medieval world.