> Russia is insignificant
You must be very naive. I do not say that in an adversarial way, but because Russia always has been (and will likely continue to be) a major world power. It is the world's largest country, with a population of roughly one-hundred-fifty million. More importantly, Russia is, along with America, one of two potentially autarchic nations. They are the only two who can not only grow food but mine their own metal, drill their own oil, etc. without importing (at least, conceivably). Isolation would of course slow either significantly, but not halt.
Consider the pressure that was on the Soviet Union, consider the inherent instability of communism, and then reconsider how long it bore up under that pressure. Russia is and has always been remarkably stable under strong, authoritarian rule (i.e. Stalin, Ivan, etc.), and any nation in a similar situation would have collapsed much sooner.