Warsw pact was created only in 1955 if I remember correctly.Perhaps a possible line is they fumble and lose control of much or all of Eastern Europe early but the USSR core holds, and does better than OTL despite losing both the resources and security buffer Eastern Europe was OTL. But clearly losing control of the Warsaw pact would be a blunder the Soviet Party would be most embarrassed by.
But inderd possible loss of buffer by librralization policies may be very possible and politically troubling for reformers in Moscow.