@Compersion what had hillary said??
WRT sunni-shia or arab-iranian fight is fight for supremacy of islam. There might be a temporary ceasefire but outright ceasefire, no way possible.
Syria even in its prime was way behind israel. So no need to further weaken syria for sake of israel, infact weakening syria may throw up radicals who may go for israel once domestic questions are resolved. More than syrians, it will be israelis who would be watching who comes to power in syria.
In this part of world, loss of face is a big thing, If gcc can't ensure a regime change, they will be ridiculed on arab street. Iran will make fun of them. This is a BIG no for gcc. After saying so many things and spending so much money if they can't dislodge assad, then their own "legitimacy" in a way is gone. Hence they themselves may be challenged in their own countries.
Even usa et al, after syaing they will punish syria for crimes against humanity now backtracks saying regime has given up chemical weapons, it may be all logically fine in west. But on arab street, message which will be put across is iran/assad managed to outwit usa. Whether that's the reality or not. but that is the message that will be put out.