In 1943 there were two attempts on Hitler's live.
On March 21 this guy, Rudolf-Christoph Freiherr von Gersdorff, was willing to kill Hitler in a suicide bombing after a previous attempt to blow up Hitler's plane failed.
An exhibition on captured Soviet weapons opened in Berlin and Freiherr von Gersdorff was the technical expert to explain the various weapons systems to the Nazi leaders. Hitler left early and von Gersdorff had to defuse his explosives IOTL.
What if Hitler would have stayed longer and von Gersdorff would have managed to gather around him all the Nazi leaders,present at the exibition before, his explosives detonate?
In the best case scenario Hitler, Göring, Himmler, Keitel and Dönitz would have been killed.
One guy would have gutted senior Nazi leadership. There was no plan for a Valkyrie-like coup attempt to my knowledge, so it is really unclear what would have happened next.
Who would gain power in Germany? How would the WAllies and the Soviets react? What course would WW2 take? Would this be the end of the Holocaust?