Thinking over Hitler's intentions, prompted another "what if" thought. Remember that Hitler didn't declare war on France and Britain, it was us that declared war on Germany, when it invaded Poland. What would have happened if we had backed down again, like we had on previous occasions?
Hitler would likely have continued his expansion to the east. I doubt that we would have bothered much when he invaded Russia - the Bolsheviks were hardly natural allies. And without allied support for Russia, Moscow would probably have fallen.
But the big question is, if Britain and France hadn't declared war on Germany, would he ever have invaded France? He certainly never intended to take on Britain, and held hopes of reaching some kind of accomodation long after we had declared war. As others have pointed out, his strategy was to only fight on one front at a time, so once France had declared war, he had to deal with that thorn in the side, before continuing his expansion eastwards. And he pretty much gave up on the invasion of France once he had got the Atlantic half, that we could have used as a landing stage. The taking of the low countries was a consequence of the war with France and the need to protect the Atlantic coast against British invasion.
A sad part of the Holocaust was that those Jews who had managed to flee Germany to the low countries and France, were trapped again once Germany invaded those countries. Hitler was initially happy for the Jews to flee Germany - as long as the German homeland was free of Jews. Only once there was nowhere for them to flee to, did some other means of dealing with them become necessary.
Would the Holocaust have happened if we hadn't declared war on Germany? It is an uncomfortable thought.