Some form of long-term political conflict? Sure. But the insanity of the Cold War, where everyone committed atrocities and backed dictators and other things because they were all convinced that an existential war was on the horizon and that anything was justified? I disagree. Hell, if you take the school of thought that Hiroshima and Nagasaki weren't about the Japanese but rather demonstrating might to the Soviets? The nuclear arms race, if it happened at all, would have been slower.
If you're starting at the end of WWII, I don't think you can avoid the Cold War unless both the US and USSR
both have a major shakeup in their leadership.
I don't think you can avoid the Cold War at all with Stalin at the helm of the Soviet Union, because I can't see Stalin
not setting up the Eastern Bloc as puppet states, and I think that's what made the Cold War inevitable. It committed the Soviets to a massive military presence in Eastern Europe, because the new governments Stalin set up couldn't survive without the threat of military intervention from Moscow. It also permanently alienated the US by confirming its latent paranoia about the USSR. It was an escalation and the dynamic it set up made complete de-escalation essentially impossible. If the Soviet Union winds up with a leader who
doesn't do that... well, you probably still get the Cold War, but at least there's a chance.
For the US... I'm less sure what exactly would need to change, partly because the years immediately after WWII are an era of American history I don't know as much about. The US right would never tolerate the USSR's existence willingly, but I suppose it's possible that with a less threatening USSR their messaging fails to get enough traction and American politics ends up substantially more leftist. If New Deal politics had stayed alive longer and stronger, then maybe diplomacy with the Soviet Union would be less fraught? Hard to say.
The problem is that neither Hoover nor Stalin existed in a vacuum. The US right and the plutocrats backing them were never going to be okay with even the
idea of atheist communism, Soviet militarization and autocracy was always going to make diplomacy difficult, and decolonization was always going to be a minefield for everyone.
On the subject of the nuclear bombings of Hiroshima and Nagasaki, I strongly recommend
this video by Shaun. Fair warning, it is two hours long, because it goes into the details of the events and people involved.
My opinion, which is substantially informed by that video, is that the bombings were not militarily necessary, but American leadership probably believed that they were politically necessary. I also think it's worth remembering that even after Trinity, nobody fully grasped the enormity of what they were unleashing. All that said, it was definitely
not necessary for the bombs to be dropped
deliberately on cities. Military targets were available.
The bombings did not by themselves make Japan surrender, but they were one of the reasons for Japan's surrender. The sharp shock of the bombings in addition to the Soviet invasion of Manchuria essentially served as one enormous wake-up slap. It also provided a convenient pretext for surrender. Without the bombs (although again, those bombs do not have to be dropped
on civilians), I think it's very possible the Japanese government would have managed to talk itself back onto the ledge
again, even after the Soviet declaration of war.