One problem for Ukraine, to be realistic, is that with no electricity they will be severely hampered, including the trains, which commenters on You Tube say are electric, and used to move troops and heavy equipment.
Thoughts?
OTOH, it seems to me Russia if it succeeds will inherit a depopulated devastated Eastern Ukraine. What the “F” (pardon my French) can they do with it, besides it being a huge liability? They sure as heck don’t have the extra people to repopulate it, as in past episodes. This is as opposed to a Ukraine victory, in which case huge Western energy and resource investment will come in.
They restored electricity. Its not easy to get rid of electric infrastructure if the owners have basic spares and supplies.
The hard parts to replace are transformers, boilers (if relevant) and turbines. All of these are or can be “hard targets”, and will require multiple hits or very accurate missiles.
One would have to maintain a bombardment to keep the system down. Rather like railroads.