What an interesting question, James. I think that, if your scenario were true, then the historical verdict on Nicholas II might be far more merciful than it is today, when the last tsar is viewed by most historians as somehow indirectly responsible, if only by default, for all the hell that broke loose after him, under the Bolsheviks. Nevertheless, IMHO Nicholas would probably still be judged pretty harshly, as a weak ruler who caved into the demands of the Germans. If you think about it, Nicholas II was pretty much damned if he did and damned if he didn't as far as World War I was concerned. If he hadn't declared war, Russia would have become all but an economic colony of Germany, whereas, once he declared war, Russia was doomed to suffer a humiliating defeat, an unimaginably bloody revolution and civil war, followed by an even bloodier and unprecedented reign of terror under Stalin and yet another world war fought against Germany. And all this, only to become economically subservient to the European Union (headed by Germany) in the twenty-first century.
Of course, if Alexei II had proved to be a great tsar (although how on earth could he have done so, given the tremendous double obstacle of hemophilia and Hitler?), then his father's reign would probably have been remembered with more sympathy. But I think that in general, when discussing the last Romanovs, we're discussing a dynasty that was already doomed after August 1914, and very possibly doomed as early as March 1881, with the assassination of Alexander II.