I personally think that regardless of WW1 Germany would have been unstable or in some form of Civil War - AFAIK WW1 has absolutely nothing to do with the Russian Revolution, apart from making 1917 a damned good time to rise up as the Tsar's Armies were focussed on the eastern front, fighting the German Empire, and thus, Socialist revolts and so on may well have spread as it did anyway - even without the War, the Nazi's were coming - whether they would ever have graduated beyond being a small group of thugs and ideas, like the BNP say in modern Britain, without the humiliation and gross stupidity that was the Treaty of Versailles is of course arguable, but without the chaos etc of the real 20's Mr Hitler would have been another Nick Griffin or Nigel Farage, an also ran.
This is a wonderful video that the BBC did for a WW1 Night - it explains the origins of WW1 via the main protagonists, the Kaiser, King George etc having a rap battle