PART I

To answer a question with a question, I would say that current-day Soviet historians would most likely respond with "Gorbachev played the biggest role in relation to what/whom?".

Let me bat out of the way some competitors for that title that have some sway in the imagination outside of Soviet and Russian studies. First, Reagan did not bring down the Soviet Union. There aren't many historians who argue this, but it is a popular idea among certain fans of Reagan and he does often get an outsized-role among academics who should know better: I'm looking at you, John Lewis Gaddis. It's perhaps more of an open question as to how responsible Reagan was for ending the Cold War (I think most historians would say not as responsible as popularly thought), but that's a different question so we should but it aside for the moment.

There are also those who have argued for what has been termed a "structuralist" approach. This can be best summarized as "the Soviet Union was a doomed experiment" approach. While this might have a bit more currency than Reagan, I don't think it's really a seriously considered argument any more. Interestingly, the one person who argued for this was Gorbachev himself: depending on the period he was writing in, he called the USSR in 1985 a "pre-crisis state" or even in a "serious crisis", mostly to argue that there was no alternative to reform (and in hindsight that he can't be fully blamed for the collapse). While some historians at the time (I'm thinking of Alec Nove) did note that the command economy was hitting a point where increasing social and economic complexity was straining the limits of central planning (Gosplan had to set prices for millions of goods), and while the USSR's economy was growing at an ever-slower pace and falling behind the social and economic conditions of the West, I think it's important to emphasize that there was not a "crisis", economic or political, in the way there would be in 1989-1991 or even afterwards. It's also worth noting, as historians on the region have emphasized, that a complete collapse of the political and economic system was not a preordained outcome of this "Era of Stagnation" - a range of communist party states have shown that various combinations of political repression and limited market reform have allowed such states to survive decades after this point.

Now, before I get into what Soviet / Russian historians think about the Soviet collapse, permit me a small aside on historiography. The collapse of the USSR is a more understudied topic even among Soviet and Russian historians than one may think. Many of the big-name Soviet historians began their academic careers while the USSR was still a going concern (I'm thinking of people like Robert Conquest, J. Arch Getty, Sheila Fitzpatrick...Stephen Kotkin is on the tail end of this cohort), and as a result a lot of the academy has focused on the first quarter century of Soviet rule (so roughly speaking from the October Revolution in 1917 to Operation Barbarossa in 1941). Even the post-1945 Stalin years tended to be ignored, and almost any survey book on Soviet history will tarry a bit on Khrushchev's years before positively racing towards Gorbachev. Which means that most of Soviet history (and almost all of the stable periods in Soviet history) tended to be overlooked! The Gorbachev years get a bit more attention, but the incredibly quick pace of events, as well as their relative recentness, seems to have meant that the Soviet History Big Names used the opening of Soviet archives to check and revise their histories of earlier periods, rather than conduct new research on that final, recent period (of course, most of the players in 1985-1991 being still alive meant that it would have been a more touchy subject anyway). The continuing pace of reforms/transition/chaos in the 1990s meant that a lot of the academics who did focus on the late Soviet era were more specifically focused on political science, or economics, and treating the 1985-1991 period as a prelude to the 1990s than as a topic in its own right (this is pretty much how any Russian politics textbook will cover the subject, eg Richard Sakwa, Archie Brown, Stephen White/Richard Rose, etc.). So proper history done on the 1985-1991 period is really only just being done right now, and as far as histories on the subject it probably really boils down to Archie Brown's Seven Years that Changed the World: Perestroika in Perspective; Gordon Hahn's Russia's Revolution from Above; Stephen Kotkin's Armageddon Averted: The Soviet Collapse, 1970-2000; and Serhii Plokhy's The Last Empire. The latter is specifically a micro-history of the final months of the USSR, and I'll single Plokhy out because he did a lot of original research (drawing on declassified documents in the Bush library, interviewing participants) and that still seems fairly unique in writing about the period. Please note in all of this I'm putting aside journalistic stuff like David Remnick's Lenin's Tomb, because it's good on the ground reporting from the era but I think it's not really written with an historian's perspective.