It's hard to imagine a real end of a conflict, even after this terrible phase of fighting ends. The best case scenario is a resounding Ukrainian victory as Ukrainians succeed in expelling Russian troops from the territory. But it would still be very imaginable that Russia would reform and recall less its troops or wait until there's a military or political opening before trying again. There are also long-term reasons why this war is being fought: empowering minorities in Russia to revolt and creating additional political instability within Russia.