UPDATES at bottom:
For now, by cutting a demilitarized-zone deal with Erdogan, Putin has removed the opportunity for US neocons to conjure up a major pretext for the Western imperial axis to attack Syria.
What Putin can do now, if Assad will grasp the concept (he's capable), is negotiate all the major players into the position that removes all support for jihadis in Syria trying to overthrow Assad, cause all foreign entities not invited by Syria to remain to withdraw from Syria, and cause the YPG Kurds and other Syrian Democratic Forces to make a solid deal with the Syrian government. In short, he can bring a great deal of peace to the area.
Assad had already said that Iran would not be staying. Turkey's only stated reason for being there is because it fears the YPG and PKK having too much growth opportunity. The US already knows regime change is not going to happen. All the powers have agreed that the groups linked to al Qaeda can't be supported militarily much longer. Israel would get its wish that the Iranians go home. Hezbollah would return to Lebanon too.
What wouldn't change though is that Syria would still be a full-blown sovereign nation with its own choice for President of Syria. The Syrians would decide who could come to and go from Syria, not the US and not the Israelis.
Putin has always pushed for reconciliation rather than slaughtering people. Assad has clearly gone along with that and appears to like the consequences. This move with Erdogan simply builds upon that platform, provided the terrorist jihadis do agree to return to civilian life under the Syrian government's rule. The foreign jihadis who invaded Syria would have to be welcomed back in their own countries.
It's all a big if, but this is all certainly a wise move on Putin's part.
UPDATE: Hey, I wrote my post above and published it and then ran into this video on RT with a pretty solid analysis by Joshua Landis of the University of Oklahoma.
Russia and Turkey have agreed a “demilitarized zone” between militants and government troops in Syria’s Idlib, President Vladimir Putin said after hours-long talks with Turkey’s Recep Tayyip Erdogan focused on solving the crisis.
UPDATE: Syria and Iran are fully on board. That's no surprise. Erdogan has bought some time and breathing room and a tiny bit of credibility but has a very long way to go to redeem Turkey and himself, if that's even possible with him.
One thing this demonstrates is that Putin's level of diplomacy is magnitudes of order higher than anything exercised by the US since the Kennedy administration at its best.