there will be no peace as long as Assad is still in power, he is a root cause of the conflict.
He btw doesn't have any army left, its Hezbollah and Iran that does the fighting and Syria will prob be their Vietnam, when the casualties becomes too high they have to pull out and Assad will have nothing left to fight with.
Just look at the Aleppo offensive, even with air superiority etc SAA failed to counter attack despite the fact that the rebels took four days to break though. They are simply not an effective fighting force, even with total control of the skies. There is no way that they can win a military victory.