'What option does Erdogan have other than changing tack , given that Assad remains unbeaten even if he is not victorious yet? '

"... This would have to entail the Erdogan government sending out diplomatic feelers to the Assad regime while indicating that Ankara is changing its position of open sympathy and support for the overbearingly Sunni opposition.
Ankara would also have to reach out to Syria’s non-Sunni minorities that it has estranged in this crisis and promote a pluralistic democratic line instead of the majoritarian one Erdogan is pursuing in Turkey, and one that also factors in the rights of Syria’s Alawites and Christians.The warning issued by Ryan Crocker, a former US ambassador to Lebanon, Syria and Iraq, to the Obama administration is also valid for the Erdogan government in this regard.“We would be making a grave mistake if our policy were aimed at flipping the tables and bringing a Sunni ascendancy in Damascus,” Crocker said during a presentation at the Council of Foreign Relations in Washington.Pointing out that there is no assurance that a Sunni government would be an improvement on that of Assad, Crocker also indicated that such a government would probably be “dominated by the worst of the worst” religious extremists..."