They endured Stalin and WW2 and still managed to improve- is it really inescapable for them to end up like NK? Cuba would suggest not, as they aren't doing paticularly badly(at least compared to NK) despite ostracism.
Cuba isn't holding down a vast multinational empire and engaging in a military game of chicken with the world's largest economy. And the USSR still had a lot of growth potential simply because it was so backwards - of course you can grow your economy if it's just basic stuff like moving people from farms to factories or building (cheap, crumbly) housing or opening new mines or drilling more oil.
I didn't mean it literally in the xenophobic state-as-a-cult situation they have nowadays in N. Korea. But the Soviet system had pretty much reached its limits by the 1980s - easily extractable raw materials were increasingly hard to find, pollution levels were extraodinarily bad, increases in productivity were almost nil. Continuing the cold war was horrendously expensive: the only way it can continue as a fundamental ideological opponent of the US is to remain a communist state, and the only way to maintain itself as a militarily formidable communist regime with stagnant or declining living standards is to force more labor out of the population and utterly repress any dissent, outside ideas, etc.
Now I suppose that if the USSR were to change itself into a fascist-Russian nationalist multinational dictatorship, it could remain ideologically opposed to the US while moving to a capitalist economy. But given Russian history, such a transformation seems unlike: Zhirinovsky was always more hot air than fire. A USSR that goes the capitalist route is undermining the logical basis of its own empire: if it is fine and dandy for the USSR to go capitalist, what is the logical rationale for Soviet military interference in Eastern Europe when they change their government? Why should it intervene to keep Communist parties with absolutely no legitimacy - now not only no nationalist legitimacy, but now no world-historical or economic legitimacy? The only excuse is "what we have, we hold."
And of course if the USSR pulls out of Eastern Europe, 50% of cold war tensions are eliminated. Throw in a few arms deals and we're at 80%.
Bruce