Copy/paste of comment by u/emorejahongkong:

Over the next 2-6 months, the best result for Putin would be:

1. The military frontline is pushed forward to constitute a relatively short semi-circle around the Northwest quarter of Ukraine (which might or might not contain the portion of Kiev/Kyiv that lies West of the Dnieper River);
2. Zelensky is alive to sign at least a cease-fire agreement along that line;
3. Order, food, government salaries and rebuilding within that Northwest quarter are each the West's rather than Russia's responsibility;
4. If dead-enders launch attacks on Russians from within that Northwest quarter, Russia probably can more easily locate, and certainly more easily retaliate against, those attackers than if they had been pushed out into neighboring countries;
5. The normie population of that Northwest quarter, finding it to be a multi-faceted shithole, emigrates elsewhere, either to the EU where they worsen the EU's energy, financial, food and order difficulties, or to territories controlled by Russia (and/or by Russia-supported local republics);
6. (Perhaps more slowly) the EU becomes heartily sick of subsidizing immigrants from Ukraine, along with the poverty-stricken and ever-more depopulated Northwest quarter, and sick of the cycle of dead-enders' attacks and Russia's retaliation;
7. Then and only then, if the West remains unwilling to seriously implement Ukraine's demilitarization, etc., it might be logical for Russia to consider pursuing an end to the formal independence of the rump Ukrainian state. As part of that end, Russian would probably benefit from offering minority border regions back to the neighboring countries they were originally carved out of.