It's ridiculous and funny at the same time to see people jumping to discussions of nuclear warfare. Nothing has happened since the shootdown, and hence nothing will happen now.
Russia knows that any action outside its scope of influence, especially against a well-equipped Turkish military, will not bode well for its overstretched assets and economy that has been struggling due to sanctions and crumbling investment ratings. By the same token, Turkey knows that it cannot even remotely afford to risk conflict with Russia, due to both a discrepancy in their military strengths as well as the fact that Ankara's relationship with NATO is being increasingly put in a limelight thanks to Turkey's habit of trading cash for ISIS oil.
The deployment of S-400 systems to Syria is and always will be but a political statement, rather than a strategically-planned maneuver. To argue this point, Russia could've easily emplaced assets that would potentially be significantly more damaging to Turkey than SAMs (land-based LACMs and Tu-95 missile carriers come to mind), but instead decided to deploy a system that is symbolic of the situation. Likewise, the lack of an appropriate Turkish counter-buildup is implicit of either Ankara's reluctance to escalate things or simply because they don't view Russian assets as a threat. Either way, it is a good development for peace and stability in the region.
It seems that some members here are more passionate about this blemish in bilateral relations than those who actually engage in policymaking. It's time to lay off the ad hominem attacks and think rationally. Cool heads prevail.
