As this has not happened yet IoTL, I'm going to stab in the dark and say no, in the event of a violent breakup, the Soviet Union will not reunite.
It is worth establishing that the breakup of Soviet Union was not peaceful. What you cannot ignore are events such as April 9th and Black January, in which anti-Soviet activity and protest was met with violent crackdown. Seeing more of these is not too hard to imagine, given how prevalent they were anyway, however if we see more Januaries, then hope for Soviet Reunification is going to have to come from the barrel of a gun, because no one would want reunification if the last memories of the Soviet Union were protesters being killed by the Soviet Forces.
Now, the extreme of this is a violent collapse in the style of Yugoslavia. In this case, the Soviet Authority, led largely by Soviet/Russian Nationalists, would try and keep what is seen as Russian in the USSR, flooding largely Russian regions would with troops and propaganda who will protect the local Russian minorities and fight the local ethnic groups to keep these regions under Russian Control. At this point, you have the Chechnya conflict on steroids, happening across the entirety of the Soviet Union. At this point, reunification is impossible.
So no, in a violently collapsing USSR, there is no hope for reunification, at all. Even attempts to invade these countries suffer due to the state of the Russian military since the end of the Cold War, and support for these states by NATO or even other regional powers will simply make it impracticable or needless. Zhirinovsky's Russian Empire explores this kind of situation, and it shows how hard it would be to reconquer the old Union.