I have less faith in the ability of individuals to overturn institutions without those institutions failing on their own. If I were just guessing, if we avoid world war 3, the West will throw enough resources at this to stop Russia from holding Ukraine. Russia wins the initial onslaught, then it becomes their Iraq 2.0. Nation building with an angry insurgency. They would have even a harder time and installing a leader they could control.
At some point the cost of this becomes too high and Russia will retreat to some frozen conflict agreeable behind the scenes by all sides. Probably close to what they already have. They'll take the East and Crimea perhaps with some strategic land grab with everybody angry about it but willing to ratchet down sanctions. Ukraine will be caught in the tug of war for the next 10 years. Maybe Putin is dead by then and doesn't have a hand picked. Successor following the same playbook. Maybe not. Maybe we get Putin 2.0 continuing to lock Russia into a losing game of cheap gas and nukes