I would have agreed that that was possible, a lot of the Empires the Russian and Austrian Hungarian empires were riven by internal disputes.
re :That by 1950 well over half of the Jews in Europe will be massacred in a period of less than 10 years.
Once again that is possible since pogroms of Jews were well known, in Europe, although I would have thought Russia before the First world War, anti Semites was not so Strong in imperial Germany although it was in Austria which was part of the Austrian Empire.
re : That one of the European great powers in a span of less than 25 years would massacre over 30 million of it's own citizens in an attempt to remake its social structure. And that these dead would be in addition to the deaths of millions of its own citizens in a great war.
Once again believable, after all we already had the French revolution and the terror from the attempt to remodel French Society followed by the Napoleonic wars. in Russia as in France we had a huge peasant base largely ignored by the landowners, and a middle and skilled working class looking for change.
Call it an alternative future history. Plausible, but thankfully, not likely, not in its entirety.