Assuming--in 1945--that the war could be ended some other way would seem to be an even less safe assumption. Japan could not have launched the war. Japan could have surrendered after Midway. Japan could have surrendered after Guadalcanal. Japan could have surrendered after Saipan. Japan could have surrendered after the Marianas. Japan could have surrendered after the Battle of Leyte Gulf. Japan could have surrendered after the conquest of Iwo Jima. Japan could have surrendered after the conquest of Okinawa.
The Japanese military government didn't.
So I've never seen how the alternative strategy--which seems to involve simply mopping up the Japanese army in China and waiting for the Japanese generals and admirals to surrender--is supposed to have worked.
Brad DeLong