We don't know that, do we? You are arguing against something hypothetical. At so many turning points of Jewish history it looked like Jews themselves, and not just a dream, would have died. There are no reasons to believe that this particular dream would've died as well.
propertius wrote: “if it hadn’t been for the Balfour Declaration, the whole dream would have died.”
And if not for the Munich Pact Hitler might have been contained and there would not have been a Holocaust.