There is the possibility of a peace settlement that includes a provision prohibiting Ukraine from joining NATO. Personally, I would say this is a reasonably likely outcome.
I’m engaging with this as though Russia’s motivations are serious, despite the fact that they’re doing nothing to actually prepare for this hypothetical NATO invasion. But even if you engage with it seriously, the failure to secure and defend Western Ukraine makes Russia totally vulnerable, NATO commitments or not. And losing so much of your military reserves doing it should terrify anyone who is actually concerned about defending Russia. Russia’s nuclear arsenal is literally the only thing protecting them right now.
