Mitch, we could put together a retirement package for Putin (as odious an option that may be). Getting agreement would be difficult -- on both sides.
Simply giving Putin a pledge of not inviting Ukraine into NATO and the EU would provide him with an achievement. But you assume that NATO was the big deal with Putin and that may not have been. He attacked Ukraine when there were no immediate plans for Ukraine in either NATO or the EU.
Putin's attack on Ukraine is mobster stuff. About territory and rent. Because Ukraine disobeyed (moved out of the fold and into Europe) it needed to be first threatened, and if not responsive, then punished.
Many thanks.