In point of fact, the Japanese Cabinet had already met and discussed terms of surrender. They had only one demand: that the Emperor be allowed to retain his throne and title. This fact was known to the negotiators at Potsdam, but they chose to ignore it as merely posturing on behalf of the Japanese government in an attempt to buy time. Therefore the argument that their response was to "kill by silence" is hardly accurate. There is substantial argument that the Allied powers did not understand the Japanese attitude toward the Emperor as one who was divine.
Be that as it may, when one considers the fact that the Japanese already considered the war lost; were attempting to get out by saving as much face as possible, and that their only demand--the retention of the Emperor--was in fact met after the bombing of Hiroshima and Nagasaki, it seems entirely likely that the Japanese would have been more earnest in their efforts to seek peace before the bomb was dropped. One must also consider that reasons other than forcing Japan to surrender were elements in Truman's decision to drop the bomb. If that is the case, any Japanese response may have been academic.
There are a couple of lines of thought with this argument. The first would be that Japan's attitude coming out of the demands made at the Potsdam Conference was so rooted in defiance that no amount of prior knowledge would have helped. When Truman emerges from the Potsdam Conference and details the "destruction" that will be visited upon Japan without a surrender, the Japanese response is to ignore it, or to engage in "yakinaoshi," meaning to "kill by silence." In this, the Japanese reaction was so steadfast against the West that little, if anything, would have persuaded them to recognize what was to come.
Yet, it is precisely this logic where some argue that Japan might have relented. Truman never discloses that he intended to use nuclear weapons, a reality that could have persuaded the Japanese to surrender or at least recognize the implications of their defiance. It is here where I think that some who argue that full disclosure would have prompted Japanese surrender might have a point to make. Had Japan realized what was going to be done, there might have been a response a bit more substantive than the political bluster of diplomats during wartime. In the end, one has to weigh out both opinions. I think that there was a definite element of resistance on the part of the Japanese, something that would not have changed until the use of nuclear weapons was felt with total and absolute certainty.