1.The mortar was definitely a false flag done by the rebels,CIA or Mossad

2.Syria does not want war with Turkey.Assad wants to get rid of the rebels.The country is ruined,there is no meaning in ruining it further with a war against Turkey

3.Turkey does not want a war with Syria because this will ruin the economy and no great benefit for Turkey will come out of it

So,the only ones that could benefit out of this situation are the rebele who want the support of NATO,NATO with a false flag attack as an excuse to invade Syria or the Israelis to mess up the whole region in order to attack Iran.

Highly possible it was a false flag by the rebels and everybody understood it and things will calm down for the time being.
If the false flag was done by another party then situation is too serious and Syria and Turkey should act wise