As always this situation has a lot of angles.
Here is another one, less related to the populations in the area, more to the interests of the parts involved.
Transnistria lesson applicated, version 3 (version 2 is Ukraine).
Unstable zone in which a civil war is going and the rebel party controls part of the country.
An outside party infiltrates the zone and claims parts of it for itself (except this time its not the russians themselves, but it doesn`t matter to them).
Strategic part of the world for Russia: Transnistria as a method of keeping Moldova on their area of influence, Donbas & Crimeea in Ukraine as they`re right on their border and they don`t want NATO at borders etc etc. ; Syria, well, 2 military (semi)permanent bases to the Mediteranean Sea in exchange for helping Assad maintain power? What do you think, they`d pass such an opportunity?
So russians send troops, arm the bases and go fight ISIS and the anti-Assad parties.
Turkey suddenly has russian neighbours (again). The kind of neighbours that don`t go overboard on asking permissions to cross airspace and that assumingly bomb pro-turkish populations or in any case people that turkish have interests in (be it turkmen, anti-Allawits or not, or even ISIS and oil contrabandists).
So the turks foolishly take down a russian airplane in order to: defend their airspace, defend friendly populations, defend economical interests in the area etc. The kind of incident the russians needed and probably counted on if not even forced it on.
And now Putin can say that him, the great crusader of christianity was suddenly stabbed in the soft parts of his behind by those cruel muslim Turks allied with the foul americans. And claim concessions, upfront or behind closed doors or pure and simple just take them and don`t care.
As before they were needed as 'peacekeepers' in TransNistria (and concessions were made there) and Donbas (concessions made there too), now they cannot leave the Syrian lands as they`re needed there to mantain peace of fight ISIS or whatever reason they can be bothered to find next (want to bet they`ll get what they want there too??).
Cause on the geopolitical chess match they`re masters. And the rest of the world plays by rules the russians don`t feel they have to respect.