It’s up to the Ukrainian people to decide. If the Ukrainian people throw in the towel, then it’s over. Of course, there will be some who refuse to give up; and thus, the war will continue, “by other means.” In which case, I’d not want to be a Russian coming out of a bar, alone; or a car full of Russians stopped at a stop light; or...well, you get the picture.
They can try.
But there has already been population movements out of Ukraine in the millions.
And there will be more leaving as the Russians annex more territory.
A lot of people have assumed that the ethnic and language mix in Ukraine will determine where the ceasefire front line ends up.
But that isn’t a fixed characteristic because of the mass population movements.
I think it is more likely that terrain analysis and military defensibility will define the Russian boundary - because they know that NATO will be facing them right across the gray zone.
And they will accept whatever terrorism/insurgency happens. Because militarily defensible terrain is essential to national survival.
In that case the eventual boundary will be either the Dnieper, or something like Ternopil and the Seret River.
lol