Neither Russia nor Iran can allow Assad to collapse and they will do all they can to prevent it.
To be honest, the current alternatives to Asaad would be worse for the Syrian people. It is always the citizens who pay the price.
BTW - Wesley Clark revealed that the neocon plan to transform the Middle East was set in the 90's and began being implemented in the 2000's. Syria was on the list and the path to Iran goes through Syria. Iran needs a Mediterranean port to export petroleum otherwise they are at risk of being contained at the Straights of Hormuz. The stakes are very high.
"One resists the invasion of armies; one does not resist the invasion of ideas" Victor Hugo