On what do you base your "certainly" assertion, other than wishful thinking?
Even if they did surrender in 1945, there would have been several tens of millions fewer to surrender, those having been killed by starvation and disease.
U.S. Strategic Bombing Survey Summary Report
Based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.
Quite true. In August 1945 the Japanese were dying at the rate of something above 250,000/week.
So if the Bomb shortened the war by more than a week or so, it was a net save for Japanese lives. Leaving American casualties out of it.
The whole argument over whether we should have used the Bomb is so idiotic I hardly know where to start. It is not based on the revulsion as to the number actually killed by the two Bombs dropped, which could have been (and was) easily duplicated using other methods of bombing. Instead it is based on retrospective acknowledgement that the more powerful Bombs developed later actually could mean an end to civilization or even all human life.
My favorite is the claim, which I’ve actually seen made, that we didn’t use the Bomb on the Nazis because they were white.
The Germans having surrendered before the Bomb was available had of course nothing to do with it.
The claim that the Bomb was dropped only to intimidate the Russians assumes (without bothering to make the argument) that this was an evil choice. Not even considering that an unintimidated USSR might have launched WWIII in a year or two.