I think this analysis emphasises too much the role of mass struggle in the demise of Stalinism and under-estimates the role played by the bureaucracy in the process. The transition process in the Soviet Union/Eastern Europe was initiated from the top downwards. It was ironically the bureaucracy - not the masses - which concluded that it could no longer carry on in the old way. The bureaucracy was a social stratum in search of a new identity and a new role in society. This led Gorbachev and his fellow travellers to chuck "Marxism-Leninism" and the leading role of the Party out of the window and introduce the market, hoping that they could transform themselves into a new ruling class running a restored capitalism. While the masses became active as a result of this, they were in almost all cases excluded from real power. They did not "destabilise the regimes" - it was the bureaucrats' experiments which achieved this. A visit to any of the Soviet Bloc countries at the time would also have made clear that, if anything, it was the intelligentsia and not the working class that was mobilised around Gorbachev's experiments.
Russell