The Ukrainian fortifications slow the Russians to a snail speed of advance but the extra manpower and hardware they have does push through in the end.
My totally out of the hat two cents tend me to believe that Ukraine will settle with a consequent territory loss.
However, Russia will never have the ability to occupy and police most of the country and will refrain to do so.
Russia may not have lost as many young men as we are inclined to believe but they have lost a lot of young people regardless....young people that will never be replaced...young people that will not participate in economic development, in innovation or anywhere Russia needs. Whatever happens, Russia has devoured a big part of its future to try to keep its image as a superpower.
Ukraine will be ruined, but might be able to join the EU, to redevelop after years of hardship.