One thing the bombs did also, was to end the war before the Soviets got involved, which most likely would have led to a divided post-war Japan, and perhaps another Korea-style conflict. Remember the Russkies wanted revenge for 1905.
The two main “revisionist” theories for dropping the bombs are: 1. We are racists, and 2) We wanted to intimidate the USSR. The underlying premise for both theories is that we didn’t HAVE to drop the bombs to end the war, the Japanese were somehow ready to surrender. They were not.
There is no evidence to support the contention that the bombs were dropped due to racism. After all, they were originally intended to be dropped on Berlin. There is some evidence that Truman and Byrnes discussed the use of the bombs and the effect it would have on Stalin, but it appears it was only mentioned off-hand on one occasion. The prime motivation for use of the bombs was to end the war.
The Russians did indeed have plans to participate in a post-war partition of Japan, specifically wanting occupation of Hokkaido and the northern part of Honshu. They were preparing for an amphibious landing on Hokkaido when the war ended. Thank God we didn’t have to deal with “North Japan” and “South Japan.” Germany, Korea and Vietnam were more than enough.