A point for the thought that Japan would not have gone to war with the US is just that a thought! They wanted to have what the europeans had land power Empire! They did that by going into china, Korea and south east Asia. To do that was to get the USN out of the water! They did for the time that Yamamoto had predicted.
As for all you B-29 lovers it was designed for the ETO and would have been used there, but to say that the atomic bombs would have been dropped in Germany that is a fuzzyer question. But Japan might have surandered with out the bombs, all we had to do was let general LeMay burn it to the ground, he hearly had already. We might have had to fight until 1946, but that was sooner the the planned invasion of the home islands.
As always the B-24 was best 4 engine Heavy!