I can't see any way to end without UN peace keeping troops
If the current regime collapses massacres will happen (by extremists who are in power of most of the opposite forces) against minorities especially alawites, christians and druzes and mostly civilians because now (according to opposite speeches) they take responsibility for the survival of the regime because of their support or even silence.
If the current regime stays this means also revenge acts on civilians who hosted the rebels, I can say that many soldiers in the army where killed (and a lot killed in inhuman ways ) and these soldiers' relatives enrolled in army (or in national defense forces which was created to support the army), you can see that the regime is currently doing this by sieging some areas and leaving civilians to die of hunger unless they push the rebels to surrender.