SA, a ruler, in this case Assad, stepping down is not going to make a difference. There are too many groups with their own agendas. Everybody thinks ONLY THEY are right, THEY want power , THEY want to rule...one way or another.
Unless people respect each other despite differences in belief, faith and opinion, the killing won't stop...look at history, it is a very good teacher. People have been killing each other for different reasons since mankind began.