1989 saw the demise of the regime based upon people power, the effects of engagement and move toward market capitalism etc...
Everything that was supposed to happen did happen.
But, the regime used its military to massacre unarmed citizens.
All the scenarios and speculations put forth here about how China will transform happened and we saw the response.
That is what happens when a totalitarian regime tried to hang on to its power at all costs. The momentum for change is piling up behind the wall the regime has erected. At some point in near future, the wall would crack under pressure, and all the pent-up pressure would be release in a big bang. Communists would not do an orderly retreat. Their retreat and demise would be a terrible mess.
And the shock wave from the big bang will reverberate around the world, probably more so than the fall of Soviet Union. The map of E. Asia could be redrawn in the process.