The basic problem for the USSR was that the costs of keeping all the actors (such as the army, security forces, and the population) satisfied were going up, while the resources with which to do this was shrinking (mainly because of falling oil prices). In addition Soviet institutions were very dysfunctional, and the economy was doing rather poorly (there was very little growth in the years from 1980-1985). The most likely scenario is either that all of this brings the Soviet Union down, or the Soviet leadership decides to try reforms and things from there go similar to OTL.