We had a discussion about the causes of World War One recently here at FR. Please remember that historically the way that kingdoms, nations, Empires etc. all looked to a war with their neighbors as a way of getting out of economic problems at home. Or to use a war to distract the masses at home away from their perceived problems through national patriotism. Also it was a great way of getting rid of dissidents too.
Right; the aggression certainly helped Putin's credibility at home. Now he has inoculated himself against his country's failing economic performance, because he will write it off on the coming sanctions. That is in the short to medium term.
Would sanctions work for or against Putin in the long run (3-5 years) remains to be seen. Historically, the Russian people rallied to the "king" in tough economic times, except one time when they destroyed the country in the process, in 1917. Maybe this time they can have a 1917 in reverse? The past 15 years or some were generally prosperous, in relative terms, so as that prosperity had generated high ratings for Putin sanctions may turn the population against him.
But I think, if the sanctions take the shape of Magnitsky law, -- denial of visas, plus bank asset freeze, then Putin's own multimillionaire buddies will shoot him.