[jfengel]

The end game is to re-conquer the politically sensitive Crimea. When they've done that, they tell Putin that they're ready to let him keep some of eastern Ukraine if he withdraws his forces from everywhere else.

"Some" could be "none", depending on their evaluation of the situation at the time. In the maximal case, they take back all of their conquered territory.

Whether Putin will accept that is anybody's guess. It is entirely possible he will reject it and continue to fight to the last Russian male and/or his stroke.