Bright day
The loss of prestige tied to not helping a friendly regime, destabilize the Soviet Bloc- afterall if USSR is retreating from positions there, it can as well retreat from its' positions here. Overall I think that by 1992 there would be no USSR.
There is a way though. The regime of Daoud Khan survives and continues it's non-alligned policy. It won't make the decisions that alienated the clergy and thus, the Soviets would never invade the country.