Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

The estimates for how many Americans would have died assaulting mainland Japan are frequently over estimated, or just misquoted.  An original estimate was "up to half a million casualties".  This got reported in histories by some as a million, but it's casualties, not KIA.  And that estimate was downward revised in later estimates.  And of course, nobody knew for sure.

When I was a kid my dad used to refer to what he called "the Ho Chi Minh, how to beat the Americans book".  The thing is, as I learned more about the Pacific War I learned that the book wasn't actually invented by Ho Chi Minh, it was invented by the Japanese and should probably be called the "Hirohito book of how to beat the Americans."
Well he could have started by not believing himself GOD and by listening to Yamamoto - who went to Universities in the USA evidently and knew the country had potential

What worked for Ho Chi Minh did NOT work for Hirohito because the US simply didn't give Hirohito enough time.  This strategy is ultimately dependent on the US not pouring in enough resources to win BEFORE US public support declines to problematic levels.  US leadership in 1945 understood this.  They planned the invasion for November, 1945 because that was as soon as they could do it and they KNEW that they were up against a clock. 
What worked for HO Chi Minh is 1st off he had Russia/China both on his side and in close proximity and supporting/supplying him as opposed to Hirohito. Secondly HO hadn't sneak attacked a country not officially at War with them thus stiffening their resolve. And that nation wasn't all in against HO like it was agaist the self proclaimed GOD. So there are 3/4 variables that were not comparable. Had the script been flipped I'm sure,HO versus China/USSR/USA after he ordered a sneak attack things would have been over in short order. And I had read that HO really wanted assitence from the USA for independence vs France and maybe it worx out differently if Washington brokers it's Independence

One factor in the bombing campaigns was an over promise given earlier in the war by folks like Bomber Harris and Lemay.  That concept was that strategic bombing could end a war almost by itself.  One stat that amazes me is that German war materiel production hit its zenith in November, 1944.  No doubt it was less than it would have been without bombing (Germans had to produce antiaircraft weapons and fighters to resist that as well).  But the daylight "precision" bombing was not practical.  So, they resorted to area bombing, and then fire bombing.  The first wave would drop HE and the second would drop incendiaries creating a fire storm.

If the A bomb was unethical, fire bombing was as well.

I think whatever killed a lot of folks is like another thing that killed a lot of folks.  My point here is that we did fire bomb Germany and the results were roughly comparable to using an atomic bomb.  Ergo, we would likely have used the A bomb on Germany.  The genesis of the project was directed at Germany (the letter Einstein signed).

The existence of nukes arguably prevented a third major European war in the 1950s and 1960s.