The most obvious point is the 20th July plot, however I'm not sure whether whoever took over after a successful plot would be able to negotiate a peace with the western allies who had resolved on total surrender. Furthermore, even though Goering (the more likely contender for taking over after Hitler was dead) would probably clear house of some of the more fanatical Nazis...
If WALKURE succeeded, Goering gets the chop. And while the Allies will still insist on unconditional surrender, unlike the Nazis, the SK regime won't fight to the last ditch. By the end of 1944, the fronts will be at the borders of Germany. The Allies' implacable determination to crush will be manifest.The SK regime will see two choices:
Surrender. Germany will be completely occupied, lose much territory, be partially occupied and looted by the Soviets, be completely disarmed, and subjected to war crimes prosecutions judged by the victors.
Fight on, which means at best holding out for six additional months. During that six months, 500,000 tons of bombs will be dropped on Germany, a million or so German soldiers will be killed, and German territory will be devastated by fighting. Then Germany will be completely occupied, lose much territory, be partially occupied and looted by the Soviets, be completely disarmed, and subjected to war crimes prosecutions judged by the victors.
IOW, all that Germany can get by not surrendering is additional beating. It will take several months for that to sink in, but once it does, the only viable choice for anyone with a conscience is clear.