Given the AGW paradigm, I'd say 7.35 years.
So, how long does Putin have left?
Sometimes you can gauge a dictator’s hold on power by the number and frequency of the purges in the upper ranks of the military. Putin may be one of those tyrants who sees his future for what it is, gathers and moves his wealth to safety, and then moves to a place of exile where he can live out his life enjoying the spoils of his treachery. Or, he will just disappear another way.