There are just two problems with your theory:
Demilitarization - before the war, the Ukrainian army was armed only with an obsolete Soviet tech. Now, they are gettings advanced western tech such as howitzers and Himars launchers, one generation ahead of its RuSSian counterparts.
Denazification - you obviously believe that there is some finite number of Ukrainian nazis, nationalists, or whatever RuSSians call them and once RuSSia kills them all, "problem" is solved, remaining Ukrainians will hold hands with RuSSians and sings "kumbaya" all together. But you know what? By its invasion, RuSSia lost support of a major part of Russian speaking population, quite possibly forever.
Eastern Europe is full of Russian-speaking Ukrainian refugees, and even Lviv people dont hate RuSSia as much, because people of Eastern Ukraine paid the highest price for the RuSSian invasion. RuSSians may be happily counting how many "Ukrainian nationalists" they killed so far, but with each victim, they just create more people who will hate them for the rest of their lives.