Whether it holds or not the Russian-Turkish cease-fire deal for Syria is hugely significant in what it reveals about the intentions of the two powers
Turkey and Russia brokered a cease-fire regime between the government and most of the rebels Thursday. Is the truce going to hold? We can not know, but the very fact Moscow and Ankara agreed to it tells us a lot about how they see Syria's future.
Firstly by agreeing to a cease-fire Russia (once more) signals to the international community that its objective is not at all to deliver a total military victory for the Syrian government. It wants a peaceful and stable Syrian state but if that can be achieved behind a negotiating table then that is its prefered path -- even if it means Damascus must grant certain concessions to the rebels.
By brokering the deal Turkey likewise sends a message -- to the rebels -- that indefinite Turkish backing until final victory in which they march on Damascus and overthrow Assad is no longer on the cards.
With Russia now invested in Syria and clearly making a difference, and Hillary defeated in the US Ankara has accepted that is no longer possible, while prolonging the civil war only benefits the Kurds.
So the rebels are being kindly advised to throw out their maximalist goals and start thinking about how and what they can get out of the war by making their peace with Damascus.
Can the Islamist rebels and the Syrian government actually make peace? That sounds very doubtful. It is also not at all clear that Russia and Erdogan's proto-Islamist Turkey can find a compromise for Syria that works for them both. But the cease-fire deal is more evidence that Turkey and Russia both are willing to give it a shot. If such a middle ground exists they will try to find it.
For more thoughts on the truce you can see an excellent short discussion with the very knowledgeable Joshua Landis: