Although an end to all violence in Syria is a nice thought, it simply isn't realistic. If it were possible for everyone to sign a treaty and make peace, the divisions between groups are too strong for it to work so easily. There are tons of factors at plays, and diplomacy is already a very complicated business. The addition of international influences and the complexity of the conflict make straightforward diplomacy impossible. Although peace should be the goal in the end, it is far off and the issue is not as simple as everyone ending the violence all of a sudden.