From what I have read Assad has the upper hand in the fight. And what started out as a more "legitimate" revolution is now more towards extremist jihadist groups fighting to control smuggling and other criminal enterprises. For Assad, at this point, to resort to chemical weapons is ridiculous, IMO, and more likely the fault, plan, or action of the jihadists.
What I want to know is will Trump deal harshly with these extremist groups if they resort to more use of chemical or biological weapons? It should be a two way street.