Sorry if my comment looks like I've seen too much movies, but even if Putin, as a human, have nothing to lose, everyone else in Russia have a lot to lose. I know there isn't lot of counter-powers but couldn't he be stopped by some Russia's agency where a lot of people have a lot to lose ? I know he have a great control over most state employed people including KGB, but doesn't this control starts to fail apart when everyone is afraid about the country being nuked ?

Bonus : it feels like a true opportunity for someone powerful enough to steal the power.