This is an interesting analysis by Mike Whitney: http://www.counterpunch.org/2015/08/14/is-putin-planning-to-sell-out-assad/
One question is: Can the Islamist Revolution unleashed by Washington be contained? Or have Washington and its NATO vassals killed so many Muslims and destroyed so many countries and institutions that there is nothing left to organize against the Revolution? If this is the case, then Russia and Iran are making a fundamental strategic mistake by cooperating with Washington against the Islamist Revolution. Instead, Russia and Iran should unite with the Revolution against the hated West.
At some point, if Muslims are to have a future, the historic split between Shia and Sunni must end. The Iranians should take the lead in bringing the split to an end. Russia and Iran should be helping the Middle East to achieve self-determination free of Western control and interventions. That is the only way to peace.