Yes, we know that it will take years to achieve "peace" but that doesn't mean there is no possibility of making peace. And I think that Putin is not stupid to carry out a nuclear bombing on Ukrainian territory.
Is Putin even predictable this days? Don't get me wrong, i am not saying Putin is going to do any of such in Ukraine, but it is much better to hope that things de-escalate pretty fast, so we do not ever have to get to stage or even contemplate such.
Having said that, the international world can't do more than they are already doing, which is attempting to force Russia to stop through imposing sanctions, i am sorry they can't do anything more than that, or let me rephrase if they do anything more than that, it could be counterproductive, and rather than de-escalate issues, it will further escalate it, take for example Ukraine's plea to the West to impose a no-fly zone over Ukraine's airspace which was rejected for obvious reasons, you can't just basically tell a nation not to fly over a particular airspace, you will have to implemet it, and HOW? By shooting down any aircraft that flies into that restricted airspace, if the international world do that, we can brace up for another world war, and that is why they won't.
So to be honest, i do not see this conflict coming to an end soon, except if Ukraine surrenders, and watching the frequent messages from their president, there is absolutely no hint at that, what can the rest of the world do? Impose sanctions and threats to Russia and attempt to cripple their economy, thus far has it done much? Not really, the war is still going on, maybe cause Russia is also very important to the rest of the world and the sanctions is hurting both ways, in my opinion, this war will only end if the both parties involved in it (Russia and Ukraine) reach an agreement, a settlement or a resolution.