The problem with Hitler, which Stalin obviously didn’t realize, is that madmen do not behave according to logical patterns.
Still, I would love to know whether, in an alternate timeline, if Hitler hadn’t been so devilish and had left Russia alone, maybe Stalin might one day have had the wish to extend his territory a little to the West…after all, why not bring Communism to the neighbors at the tip of the bayonet, if good words don’t avail anything?