There is absolutely no way to know what would have happened if Hitler had won World War II. There are many works of fiction that address the subject such as the 1988 novel "Moon of Ice" and the 1967 Star Trek episode "City on the Edge of Forever."
Of the many counterfactual histories and works of fiction available, the conclusions vary widely. Some predict an eventual nuclear confrontation between Germany and Japan, while others claim there would have been a softening of racial prejudice and a moderation of the Nazi policies in a post-war world.
Conservative pundit Pat Buchanan claimed in his 1999 book that Hitler would have defeated Stalin, and there never would have been a cold war between the United States and Russia. Another theme in British and American fiction is the idea of collaboration between the Nazis and the Allies. Phillip Roth's 2003 book "The Plot Against America" is an alternate history in which Charles Lindbergh defeats FDR and allies with Hitler.
The historical evidence is clear that Hitler planned to continue his extermination of the Jewish people in Europe. There is also ample written evidence in Hitler's correspondence of plans to attack the U.S. mainland, specifically New York City.