The scenario is far fetched at best and improbable at worst. Until and unless Assad looses his nerves and runs. Reason being, had the US and West wanted Assad gone, he would have been gone by now. The oft leaked reports of US arming the moderate opposition is merely a hogwash. The support to the opposition, irrespective of AQ links, ISIS or otherwise, is chiefly by the troika of Turkey, Saudi Arabia and UAE with other Sunni nations also marginally involved. Reports have emerged of Pakistani ex-servicemen being deployed there with these groups too (how true, can be dependent on which report you believe) with money being sent to their families by these countries. It is an open secret that the Saudis bankroll the Pakistani Army and its nuclear research to protect itself. The whole scenario is further complicated by the tacit understanding between US and Iran, with the latter actively involved in organizing, arming and leading the operations on behalf of Assad. The US is also becoming wise to the fact that its biggest ally in middle east is mot necessarily working in its favor. The increased likelihood of a deal on Iran's Nuclear Plans is also an indicator of the slow but steady shift in US and West's policies in middle east. The plummeted oil prices due to the activation of Shale Tech in US is also something that has been a deliberate ploy, IMO, to starve these 'rich' OPEC countries who are now working against US' interests. With the recent events in Yemen, Houthis targeting Saudi Arabia, the dynamics have drastically changed. Even if the opposition were to win in Syria, the result would be increase destabilization in Turkey from Kurdish movement and other pro-Assad elements (remember irrespective of whatever one may say of Assad, the society was progressive, educated and economically well off. And religious harmony is a hallmark of his rule; so the Islamic victory over there will be something that will fracture the society as it is increasingly being dominated by AQ and ISIS!) And for Saudi Arabia - the stakes will dramatically change, Iran will ensure that it gets the West and US on its side, even if it has to compromise on its nuclear program (and it may just ask Russia and US to give it guarantees against any nuclear threat; remember Pakistani nuclear program is financed by the Saudis, they may ask for a couple of nukes) and then it will ensure that KSA is in a mess once for all. The emir is anyways not liked by his people, he is only in power as long as US is backing him and his army. The moment a pressure is applied on KSA, the people will rise against both Iran and the Emir!!!!
