The flaw in the analysis is Putin is very popular even while Russians detest United Russia.
Putin has managed to distance himself from the ruling party of power even while corruption in Russia is rampant and the rule of law is questionable.
This is exactly why he needs Crimea - to show his core supporters the weak Russia of the Yeltsin years is a fading memory.
And he does not care in the least about Western opposition to his political needs at home.
Russia has its cyclical ups and downs. 1/3 of the country is made of autonomous republics, Chechnya, Tatarstan, Tuva etc. When the next “smuta” comes, neighbors will do with them what Putin is doing now with Crimea.