I can understand/appreciate both sides of this coin. At any rate, I found an online rendition of an official US government assessment which is interesting and contemporaneous...
Note: I cannot post the link due to insufficient post count. Just Google the document title
UNITED STATES STRATEGIC BOMBING SURVEY
SUMMARY REPORT
(Pacific War)
WASHINGTON, D.C.
1 JULY 1946
Page 26
[...]
There is little point in attempting precisely to impute Japan's unconditional surrender to any one of the numerous causes which jointly and cumulatively were responsible for Japan's disaster. The time lapse between military impotence and political acceptance of the inevitable might have been shorter had the political structure of Japan permitted a more rapid and decisive determination of national policies. Nevertheless, it seems clear that, even without the atomic bombing attacks, air supremacy over Japan could have exerted sufficient pressure to bring about unconditional surrender and obviate the need for invasion.
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.
Note: I cannot post the link due to insufficient post count. Just Google the document title