As both Russia and Ukraine race to redeploy troops toward eastern and southern Ukraine, where a battered Russia still hopes to gain new territory that it can then proclaim to have been part of Russia all along, much of what happens next is contingent on the Russian military being able to either recommit those forces or muster suitable replacements. That's not necessarily a given; while the news is now filled with images of the atrocities Russian troops committed during their brief occupation of towns north of Kyiv, the retreat also brought evidence of even heavier Russian losses than previously known.
A good chunk of Russia's entire deployment of tanks, in particular, has been either wiped out or captured. And while we might expect that Russia might have better luck resupplying forces through Russia than it did from Belarus, that's not a given either. Ukrainian forces have also suffered heavy losses—but an influx of NATO weapons is boosting what was lost, and Ukraine has more defenders willing to fight for it than it can properly gear up.
A Russian move to annex Donetsk and Luhansk is in theory a more achievable action than Putin's previous grab-it-all approach, but Russia has already thoroughly wrecked much of its own standing army, it has already been begging China for military gear it was thought to have already stockpiled in mass quantities, and we simply cannot guess how much of Russia's supposed military might has been stolen from its warehouses by a Putin-led kleptocracy that has shown utter contempt for the nation it claims to lead. And the sanctions Russia now faces won't be going anywhere for a long, long time.