"Conclusion: Make peace with the devil you know, not with the one you don`t know." The devil Israel knows is Assad ; he's the one Israel should try to make peace with. Whereas it's not easy -maybe impossible- for Israel to "crash" Assad's regime AND TO settle a new one ; I sincerely think that in such a situation, the regime that Israel would try to settle would be seen by Syrians as traitor, and Israel would face the Islamists, who would play a national leader part, like Nasrallah did in Lebanon. That's why it's intelligent to talk to Assad, who is nationalist, but not Islamist.
Shaffir to Herzog: Opposition failed to show leadership in political battles against PM (Haaretz)
from the article: A war in the summer?