Assuming a time line in which the communist party does not remian in power in Russia itself which nation of Eastern Europe (or ex Soviet republic) has the best chance of remaining committed to communism. I have always found it interesting that even a nation like Albania that had split with the USSR a long time previously was not able to weather the general collapse. Would it have been possible for some nation like Yugoslavia or Albania to survive the general collapse. Or prehaps for one of the ex- Soviet republics like Belarus to remian committed to communism?
Once Gorbachev made it clear the Red Army would not intervene to guarantee the continuity of the communist system in the Warsaw Pact countries, the genie was out of the bottle. The 1989 summer protests in Hungary could have fizzled then and there had Gorbachev been willing (or able) to perpetuate the Moscow Doctrine (like the Monroe Doctrine in its own way).
The moment it became clear the ruling elites would not be propped up by Soviet tanks the question then became whether said regimes had the capacity to adapt quickly to the changing circumstances. Sclerotic as they had become, the inevitable outcome was in the negative. Indeed, in Czechoslovakia, Poland and Hungary, Communism fell not with a bang but with a whimper - the whole edifice was found to be built on sand. As with other internal political collapses (France 1940, South Vietnam 1975), it wasn't as though they lacked the means to survive but they lacked the will.
There were two variations - in East Germany, the initial demands were not for reunification but as the way to the West was opened, the state itself faced the notion of becoming unviable via depopulation. In 1989-90, there was a migration, especially of young women, from the DDR to the FRG - the Berlin Wall had done what it was supposed to but once it fell, the issue which had bedevilled East Germany in the 1950s returned with a vengeance. In 1990, the idea that was the DDR walked or drove to the west - it left a country of young men and older people which couldn't survive economically - unification became an inevitable consequence but it was not what those in New Forum or those marching in Leipzig or Dresden in the autumn of 1989 had wanted.
As for Romania, unlike the other East European countries where, while changes to the leadership had occurred within the Party, there was no sense of a dynastic approach, Ceaucescu had made the country a vassal to him and his family. Oddly enough, it was more akin to Saddam's Iraq than Honecker's DDR. Ceaucescu's flight and end was a mixture of what might have happened to Saddam or to Mussolini under different circumstances. Once the power of patronage and terror was broken, he and his family literally had no one and nothing. No one owed them residual loyalty or respect so their lives were forfeit in a way Honecker's wasn't. There was little or no sense of a bloodlust in other Warsaw pact countries - they might have wanted the old leadership gone and perhaps tried but there was not the desire for physical revenge witnessed in Bucharest. I've little doubt Ceaucescu would have been lynched by the mob.
The sudden nature of the fall of the Communist leadership left a huge vacuum - in those countries which had at some point resisted Moscow, those survivors of that resistance came back to prominence be it Walesa and Dubcek to give two examples. Dubcek still thought, pace Gorbachev, it was possible to reform communism but the tide of history swept past him to Havel.
In Romania, there are plenty of accounts of various groups making it up as they went along in radio and tv studios - without a centralising opposition figure, what you saw was a coup against Ceaucescu and his family by those communists who had been marginalised by the dictator such as Iliescu. It wasn't a complete rejection of Communism but a rejection of the leader, his family and their entourage.
