Capturing area and holding area are two different animals.
Unfortunately holding may not be relevant.
Russia will take Donbas, control the south, then call for a ceasefire.
Countries like Germany, France, US will call for ceding the area for “peace”.
“Capturing area and holding area are two different animals.”
Donbas will be turned over to the local militias.
They will hold it.
Easily.
Moreover, the introduction of large caliber modern US and NATO howitzers is strengthening Ukraine's conventional artillery, while the provision of highly accurate, long range US made MLRS and HIMARS rocket artillery seems imminent upon the completion of training. If so, Ukraine could then impose heavy casualties and rollback large swaths of Russia's territorial gains.