Last week, Russian troops left Northern Ukraine and regrouped on the Eastern border. Officials believe this was a “plan b” move to seize control of the Luhansk and Donetsk territories in the Donbas region of eastern Ukraine and secure a land bridge between Crimea and the Donbas. If this is Putin’s current goal and succeeds, I would imagine there being a possible stalemate.
Of course, such an action would require at least half a year if Russia can maintain its momentum and forces. As you can see on the map below, Mariupol, a port city, is under Russian control. Even though it is past the front lines, there is still a resistance there attempting to evacuate civilians. Officials project that the city may be destroyed and taken over within the next few days. This loss will be a significant blow for Ukraine as Mariupol is the last occupied port city on the Southeastern border. I believe that Ukraine should launch counter-attacks on Russian supply lines, hindering their attempts at getting armored vehicles into the regions; since Western weapon technology has proven to be vital in deterring advancements by Russian forces.

https://www.reuters.com/world/europe/mariupol-may-fall-within-days-european-official-says-2022-04-19/

https://www.bbc.com/news/world-europe-60506682

-Luke H