Short answer: we’ll just have to wait and see.
Based on the shooter’s statement, as recorded in the video of the incident, the Russian ambassador was killed in retaliation for Russian military actions in Aleppo.
If that proves to be the case, as seems likely, it is apparent that Russia is now being made to pay for supporting Assad and keeping him in power.
As yet no organization or nation has taken responsibility for the killing. But this we do know: the shooter was a member of Turkish police forces.
Who will Russia blame? There is no shortage of possible culprits. The Kurds, ISIS, Syrian rebels, even Turkey — all may be considered suspects, at least for now.
We can only speculate as to how Russia will react. Much will depend on who gets the blame.
We have our suspicions. And we suspect that the answer may surprise you.