Assuming you are talking about the real Nazi party of OTL and not just any old nationalist/fascist Versailles revisionists, it would have died out without Hitler. I tend to be follower of the "great man" doctrine of history, and there were probably few people in the Germany of 1919-1933 who had the right mix of intelligence, drive, anger, charisma, aesthetic vision, and controlled (at least a first) insanity to develop and dominate such a radical movement as pure Nazism. Goering and Himmler would have failed miseably at leadership, Goebbels was probably too sane, and Hess...well who knows. A Hitler-less Nazisim would probably have lost itself in a coalition of populist right-wing parties and causes...and a lot fewer people would have died at the hands of Germany in the period 1939-1945, even if there was a WW2.