Yes it was, the era of stagnation started with either late Khrushchev or Brezhnev, but the USSR in 1985 was a stable political entity.
You didn't need Stalinesque repression to keep the Soviet Union stable. Khrushchev-Brezhnev-Andropov-Chernenko era USSR were perfectly capable of suppression dissent which threatened Communist rule: from both within and without the party.
I would disagree. The situation was bound to become worse without massive reforms. This would have created more and more dissent. I doubt that the means of the Brezhnev era would have been enough to surpress the level of dissent that would have resulted from continuing business as usual while the economy slowly rots.
How would the Soviet economy look like in 1995 or 2000 without any attempt to reform the system ? Lets not kid ourself the economic situation was disastrous the Soviets were racking up debts and the "means of production" were slowly rotting without the necessar investments.
Dissent would have exploded in such circumstances.
And lets not ignore the West. We wouldn't have seen the help of OTL. Probably the opposite. How would your hypothetical Soviet Union survive the embargoes and sanctions of the West? I doubt that western politicians would stand by while KGB and Red Army are violating human rights left and right