1) Is there any evidence that economic turmoil would cause population decline is Russia? Soviet demographic statistics don't show historical correlation between the two.
http://upload.wikimedia.org/wikipedia/commons/7/77/Population_of_Russia.PNGIn fact, the two values might be inversely correlated.
http://rstb.royalsocietypublishing.org/content/364/1532/3023.full2) Overall, the analysis seems sound. Now that China has taken a stance similar to the West, Russia is being threatened by economic ostracization to some degree. As large Russian enterprises have lost considerable stock value, Putin's constituent oligarchs might indeed expect a change of policy or start searching for a new president.