There's the argument made by
@Skallagrim that the French Revolution was a lightning in a bottle situation that was unlikely to happen at any other time, but I've heard many others say that an event like that was only a matter of time, and Russia is probably the most fertile ground for a Radical Revolution of any country. It has all of the same problems that Ancien Regime France had (an out of touch aristocracy, a restless urban middle class that had little representation, economic issues, bad harvests etc.). It's no wonder that Russia was the country that went Communist IOTL, albeit not without a nasty civil war, which I think is quite likely ITTL too.
I stand by my view on the French Revolution, although that doesn't imply that all radical revolutions are vanishingly unlikely. OTL (in both the Russian and French cases, as well as other examples) shows that you need the right (or, as it often turns out, the
very wrong) combination of 1) certain serious pre-existing tensions, 2) a government that does things the exact wrong way, 3) a direct impetus that allows for matters to get criticial, and 4) certain random decisions that happen to push things over the edge.
France and Russia had (1) and (2) in spades, as you've noted. In both cases, (3) also came about: in France, dramatic crop failures that hit France disproportionally hard because of the Frenxh mercantillist policies, resulting in food shortages that soon escalated into uprisings; in Russia, World War One and the way this totally wrecked the country, compounded by the fact that Russia lost and the government accepted a humiliating peace. I note that in both cases, even a
single serious stroke of good luck would have staved off the crisis sufficiently to prevent things from going critical. This wouldn't mean smooth sailing, but there would have been just that little bit more lee-way. And then there is (4), which in France came down to a number of easily avoidable decisions (e.g. the precise circumstances of the way representation of the Estates was handled; the precise wording on
one speech that was unintentially inflammatory...); and which in Russia boiled down to the easily-butterflied fact that the Germans sent Lenin over to cause trouble, which went "horribly right", as they say.
My point isn't that revolutions are so unlikely, but that you need the circumstances to be just right for them to actually go through. Saying that conditions (1) and (2) are met isn't sufficient, and even meeting condition (3) is no guarantee; you still need that one random fuck-up that results in condition (4) being met. That being said: it isn't hard to contrive such an eventuality, nor is it implausible. Russia, given a path similar to OTL, does meet the first two conditions, so given the right crisis and the right "horrible variable" occurring, it is a likely candidate for some kind of revolution.