completely unrealistic, demographic transition occurs as income rises, fertility rate would have plummeted in atl Russia by the 1950s or so because a Russia without the world wars and civil war would have being a lot richer
I find the straight line it draws pretty unrealistic too.
More likely the Russian population would go up exponentially before starting to level off. Now, it could start to level off anywhere between the 1950s to the 1990s. It depends on the political, economic and cultural evolution of the empire.
For example, does it stay on the course it had been on since the botched ending of serfdom, meaning excessive population is retained in rural areas, meaning demographic transition happens later? Do the political and cultural forces that kept peasants on the land get broken relatively early? What role does the Orthodox church have? How does the Tsarist regime respond to events like the great depression? What happens in China with a more expansionist northern neighbour during the 20s and 30s?
And when it does level off, how fast it levels off is also an interesting question. In OTL, the Soviets shifted from a 3rd world growth rate to a 1st world growth rate and then kept that until the Soviet Union collapsed. But what may happen is that Russia in an ATL might go from a high growth rate to very low/negative growth rate very quickly, more like what happened in South Korea.
IMO, the later Russia enters its demographic transition, the more likely it is that it does so sharply. Mostly because whatever happens, Russia has a limited resource base, and at a certain point, people will decide that they don't want to bring children into the Russia that exists around them. Not necessarily because their environment is so miserable, it may simply be that life is comfortable, but so much effort is expended on keeping it comfortable that people don't have much time to find mates and have children.
fasquardon