“The thing I worry most about is how Ukraine can replace their personnel losses.”
Often, when a country is fighting to defend its very existence against an invasion, ordinary people step up. They may not be front line troops, or well-drilled, but they can contribute to the defense.
Exactly. Ukraine is fighting for its very existence. They are fighting an enemy they remember as starving off 1/6th of the population of Ukraine only 90 years ago.
There is an effective source of about half the population of 40 million willing and able to fight.
The Russians were in that position in WWII when the NAZIs invaded. They were fighting for their existence. Now, the Russians are the invaders.