In January 1946 alone, the US was supposed to drop more bombs on Japan than it had done all through the war up to that point.
The Japanese economy as whole would have collapsed. Every bit of infrastructure would have been wrecked. The nation would have been utterly cut off from its empire and world trade, so excluding all oil, steel, rubber, etc., etc.
Should it have turned into invasion, the Soviets would have most certainly invaded Hokkaido and the Americans Kyushu (with the Brits reclaiming Malaya and the Chinese Singapore).
Japanese deaths would have totaled millions. Millions more Malaysians, Singaporeans, and Chinese would have been dead under Japanese control.