Another communist revolution in Russia you mean? Well the chances of it happening for a second time are certainly possible I think, given that Imperial Russia has, yet again, lost another major war - discontent within the empire would run high and the communists are still roaming around, but as small insurgent groups. I'm not sure if it would succeed or fail though really. The communists were crushed pretty hard during TL-191's Russian Civil War, with many of the revolution's recognizable leaders being killed, including Stalin and Molotov - well that might be an exaggeration, their fates are not known, but if they were around I believe would have heard more from them. Localized uprisings might be possible, but the memory of the first civil war would still be on the minds of every communist still in Russia. They'd have to have better organization and competent leadership to try and dislodge the Romanovs again and this time the regime would clamp down harder than before. I'm not saying its not possible, I'm just emphasizing that the communists would be fighting more of an up-hill battle, even with the Imperial regime battered.