Significant visible change at the top in Russia has to happen, in my opinion.
On many levels there are such comparisons with WW2. The Germans couldn't win the war probably after a short period around Dunkirk (as long as we had US support and held India and the rest of the empire), but they had LOST the war by mid 1943 and it was evident to the German high command, the front line soldiers, sailors and airmen and most of their civilians by mid 1944 that Germany was not only going to lose, but it would lose ever more catastrophically, in every respect, the longer it continued to fight.
Russia had that small initial window of a few days to take Kyiv, capture and replace Zelensky and win. It is now a case of how long can they prolong things and what will be the ever increasing cost.
So why didn't Germany actually surrender?
Because those at the top knew that it would mean death for them personally and the Nazi ideology that most of them fervently believed in. The survival of Germany overall and the suffering of it's people came nowhere in to their calculations. Therefore the only way to get Nazi Germany to surrender before their military was destroyed, their cities and industry razed to the ground and the Red Army exacting terrible revenge all the way to the Reichstag, was change at the top. That was easier said than done. It was even more difficult after the failed Von Stauffenburg plot, so it is important that when moves are made they are successful. Treason is death. Failure is death. Even association with traitors was death, just look at the fate of Rommel.
We are in a similar situation with Russia now, it seems to me. The one (huge) difference, at the moment, is that Ukraine and the West are not going to invade and destroy Russia. Never the less, just as with Nazi Germany, war will continue until those in charge of Russia, those prime movers, those influential powerful key figures who also believe in the war in Ukraine, believe in Russian expansionism and believe in Putin's kleptocracy, are removed. If they are not, then at best we will have only a pause for Russia to re-arm, learn, plan and return.
If we get to that then it would seem that the West will be back in a cold war situation, with Poland, Ukraine, Latvia etc on our side of the curtain, but China, India and others now as viable significant economic outlets for Russia.
Even to get to that cold war situation from the hot war we are in, Russia surely either has to have a genuine change at the top or a visible, apparent pretend/slight change at the top, to allow Ukraine and the West to even contemplate a deal could be struck that has any viability. We probably won't know for quite some time which, but there will have to be some high profile victims prior to any withdrawal and reparation negotiations. Shiogu would be one visible change. Putin even better, of course, but if he doesn't die then there needs to be such changes that he is an isolated figurehead no longer in charge. I can't see that happening because it is just not the Russian way. It might happen in practice, but he would die soon after, before the world started laughing. So opaque, careful, weird moves going on in Russia don't worry me too much. There surely have to be some on the way to the outcome we need, it's just whether they are the right ones, or perhaps counter moves. Russians are still pretty good at ruthless political chess on their own boards.
Russia is still heading for some very difficult economic times whatever happens. The full catch up consequences of this wasteful war will have quite some time lag. Russia had some very unsavoury demographics coming along, it now has more. It doesn't seem like the most welcoming place for a bunch of young Nigerians say to rock up. In terms of influence worldwide it has lost it's military reputation for competence and it's arms industry credibility is in tatters for everything except maybe drones.
Furthermore, in the same way WW2 was the end for Britain as an empire and world power, it could do the same for Russia. It may break up. It has certainly lost the fear factor of some neighbouring states. The EU, NATO and China will be preferred partners.
So, tough economic times ahead for Russia, even with its natural resources. If there is a genuine change at the top, the tough times ahead might end up being laid at their door and allow another Putin or Stalin back in. It might be better for both us and Russia all round if the change is not genuine and a new cold war ensues. The economic difficulties coming would be exacerbated with continuing western frostiness and we might have another collapse of regime as happened 25 years ago. Many people in Russia have got used to some significant improvements in the last 25 years. It is always more disgruntling going backwards to poverty than never having reached a position of comfort in the first place. There are millions more young, intelligent, productive Russians who have or are enjoying life outside Russia that it can't afford to lose but are unlikely to return to a life worse than they have in the west.