There would be a power vacuum, probably a few murders/suicides/defenstrations, and the elections scheduled for a few months from now will probably be postponed during the struggle for leadership of the country. My guess is the powers that eventually take over will agree to pull out of Ukraine, conduct a few show trials, and do whatever else they think they have to in order for the west to lift the sanctions and unlock the oligarch’s accounts.
It would please me greatly to know that Ukraine will outlive Putin.