This article describes how some "rebel groups" are, among themselves, actively discussing the possibility of peace with the Syrian government. That's a good thing obviously, because until this point in time they rejected any such accord. But to be clear, the groups that you and I would refer to as "rebels" are far fewer in number and fighters than the groups we would call "terrorists." Islamic State is an obvious example of such a group, and it will never agree to give up the territory it controls in east Syria.

The "rebel" groups in Syria such as the Free Syrian Army, were actively supported by Turkey, the USA and others. So with Russia and Turkey talking peace, there's a reasonable possibility that those groups will lay down their arms. The Islamist/terrorist groups that control territory in western Syria are unlikely to do so, but they may agree to leave under a cease-fire and join up with Islamic State in the east.