If Hitler was set on genocide, why was there ever a plan for relocation of the Jews?
That was an entirely reasonable question by wbell, and David Frankenberger was mistaken in dismissing it out of hand. In discussing the question of Hitler's long-term intentions, there is no substitute for solid evidence, that perhaps David Frankenberger was unaware of.
For example, on two occasions early in 1940, Eichmann's office at the RSHA in Berlin asked the Soviet immigration authorities to allow the Jewish population of the German-occupied General-Government of the Occupied Polish Territories to be transferred into Soviet territory, on the basis of the German-Soviet agreement on mutual population exchanges that had been reached at the end of September 1939. The Soviet authorities refused the request on the grounds that that agreement provided only for ethnic Belarusians and Ukrainians to be transferred to Soviet territory.
A German request for the Jews under their control in the G-G to be transferred to Soviet territory is self-evidently inconsistent with any ostensible intention by Hitler to subject them to genocide at some future time, since once they were under Soviet control they would be out his reach. The request by Eichmann's office was simply a continuation of earlier efforts by German authorities right from the beginning of the invasion of Poland to push the Jews of the German Zone of Occupation eastward into the Soviet Zone, eg Heydrich's order to concentrate the Jews in areas contiguous to the inter-zonal Line of Demarcation, first east of Krakow, then in the Lublin District after its transfer (at Stalin's request) from Soviet to German control.
All the actions of the German authorities from September 1939 to the middle of 1940 suggest that the plan endorsed by Hitler was to transfer the Jews of Poland to the Soviet Union, most probably followed by the Jews of Greater Germany itself (Germany, Austria, Czechia), in all some two million persons. After the fall of France, that plan was superseded by the well-known plan to transport those Jews, plus those of Western Europe and of Germany's East European allies, to Madagascar, a plan that was frustrated by the failure to force a British surrender. The final phase of these deportation plans was reached after Hitler's decision in December 1940 to go ahead with the invasion of the Soviet Union, when planning began on the mass deportation of all European Jews into conquered Soviet territory, which was scheduled to begin in the spring of 1942, after the expected final defeat of the Red Army and the overthrow of Soviet power west of the Urals.
It was only after the failure of all the relocation plans, as a result of the failure to achieve a decisive victory over the Soviet Union by the end of 1941, that those plans were replaced by mass killing. The evidence suggests that the replacement was initiated by local German authorities faced with the burden of having to house and feed large numbers of imprisoned Jews, and was subsequently endorsed by Hitler at some point in time that cannot be determined precisely (historians disagree as to the timing). The evidence also suggests that the mass killing began as a series of localised limited actions that eventually expanded into a comprehensive genocide by about May 1942, and took on a momentum of its own. Even so, there were variations in the pace of destruction, at times intensifying, at other times slackening, apparently in response to Germany's fortunes on the battlefield; once defeat became inevitable, the mechanism of destruction began to speed up, but paradoxically became increasingly impeded by the need for more and more Jewish slave labour.