Valkyrie was for nothing?

Lets suppose that valkyrie was successful and the conspirators did manage to kill adolf hitler and take over the german government. Did they really think that the allies would bargain with them? Wasn't bargaining way way way off the table a longgg time ago? The only thing the big 3 wanted was the complete elimination of the nazis and the unconditional surrender of germany. They would never have given any type of surrender terms with victory so close at hand. Am I wrong?