Peace comes when both sides decide that they have nothing further to gain from fighting.
If, we understand that criteria for peace, then when Russia finally takes over Ukraine, despite the US’s attempt to push their own offensive, what is there to stop the war at that point?
The west has depleted its weaponry, shown it is led by incompetent fools, politically, militarily, intelligence wise but also critically economically. Russia knows at this point, it could relatively easily (in terms of the way Russians think), bring it’s enemy to its knees, but, unless Europe and the US accept their defeat, unless they commit to no further provocation of Russia stirring up war, then war is inevitable. So, why would Russia wait for its enemies to learn the lessons of this attack on Russia and to reequip and resupply and next time kill even more Russians?
The problem is that the delusion amongst western politicians and media, is now so intense, that I do not believe they will accept peace. As such, Russia cannot stop at the border of Ukraine. Instead it must continue, albeit, not necessarily initially by overt military means which give the US an excuse to kill a lot of USians.