The reactionary countercurrent in 1989 was preceded by a series of failures in economic policy. Before the USSR's liberalization in the Gorbachev era there was already a (probably survivable) economic decline. Changes in trade policy, in particular the massive reduction of subsidies in 1985-1986 caused massive economic problems in the already struggling Comecon nations, who had largely based their economies around receiving these subsidies (particularly energy subsidies, their industries were massively energy-inefficient). You can see this in the periods in which structural adjustment started in most Soviet allies around the world (a lot of people don't seem to realize that most started 1986-1990). This economic decline led to larger public discontent thanks to widespread goods shortages (and is the real source of Poles pissing their pants screaming about shortages).
Additionally, there was the ideological component. If you're a communist ally of the USSR to the point of typically adopting their party line (as was the case in European socialist states), and the USSR just utterly internally capitulates ideologically, what the fuck do you do? The beacon of revolution is now saying they want to transition to social democracy. How do you maintain a strong face? Repudiating Stalin was ideologically problematic, but openly repudiating communism as a whole relegates communist parties to the trash.
The whole Soviet bloc was leaning on the USSR and couldn't stand independently without it. Some third world revolutionary states survived via structural adjustment. Cuba suffered greatly but managed to survive. China had distanced itself and became more autarkic and independent. The DPRK had as well, but not as dramatically. The other socialist states outside of the USSR's camp (Albania, Yugoslavia) were too dependent on their leader's personalities for socialism to survive without them.